When Engine Instruments Lie

Remember Air Florida Flight 90, the Boeing 737 that crashed into an icy Potomac River after takeoff from Washington National Airport in January1982, killing 74 of the 79 aboard? A contributing factor in that accident was anomalous engine instrument readings caused by ice-blocked EPR pickup tubes. Retired 737 captain and AVweb contributor John Laming tells of experiencing a similar problem, on takeoff from the tiny Pacific island of Nauru, which brought him to within seconds of disaster, saved by the actions of a quick-thinking pilot-in-command who was subsequently crucified by the airline whose airplane he saved. It's a fascinating story of technical intrigue and political injustice.

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SafetyInwriting this article, I am reminded of the often-used patter by younginstructors in which the student is told to keep an eye on the enginetemperatures and pressures during the takeoff. The reality is that oil andcylinder head temperatures are slow to indicate trouble, while oil pressureneedles can flicker and vary by small amounts depending on engine power and RPM.A sudden drop of oil pressure near liftoff could be an impending engine failureor a gauge malfunction, but there is simply no way of knowing for certain. Alate abort for an engine gauge reading, when combined with a limiting runwaylength, has all the potential for an overrun accident.

The correct time for a last-minute assessment of engine health is at brakerelease, with priority then given to directional control, lookout, and airspeedindications. Good airmanship dictates that a critical stop/go decision shouldnot normally be based upon one gauge alone. Always check for corroborativeevidence before committing yourself to an irrevocable course of action.

The following incident happened on a dark Pacific night, where a seeminglyimpossible combination of factors caused a B737 to come just a few seconds awayfrom disaster.

Air Nauru…

Boeing 737Thebest job I ever had was flying a Boeing 737 for a small airline, which was basedon the tiny island nation of Nauru just 27 miles from the equator in the CentralPacific. The nearest daytime alternate was 375 miles away and a night diversionmeant 500 miles to the Marshall Islands, or the burning of one’s bridges of twohours island holding fuel, followed by landing or ditching! Our destinationsincluded many of the Pacific islands between Hong Kong and Honolulu, theSolomons to Rarotonga, and New Zealand to Fiji. Our air hostesses all spokeEnglish in a variety of charming regional accents and many were natural dancerswho had been taught from childhood that music, laughter, and dancing was allthat was needed to enjoy a full life.

We flew the popular Boeing 737 with most of the pilots expert at short-runwayoperations and black-hole approaches to remote islands. Some of us had beentrained in the Royal Australian Air Force (RAAF) and our number includedexperienced ex-fighter and transport pilots. Other pilots included Americans andKiwis, while the remainder were Australian GA pilots who had been employed oncharter and instructor flying before getting that lucky break into an airline.

The runway on our island base was 5600 feet long, with a road cutting acrossonly feet from each end. The overrun area was just 100 feet from the ocean, withthe prospect of fatal damage if the aircraft collided with huge phosphate rockboulders which formed the sea wall. In the wet season, strong southerlies meantcrosswinds up to 30 knots while huge waves whipped up by the winds dashedthemselves against the rocks, sending mist and spray over the threshold.

…and Air Florida

Readersmay remember a widely publicized 1982 accident involving Air Florida Flight 90,a Boeing 737 that crashed on takeoff from Washington National Airport as ittried to get airborne while covered in snow and ice. The aircraft was unable tohold altitude and, after hitting a bridge, crashed nose first into the frozenPotomac River. The FDR was recovered and its evidence showed that the engineshad not delivered full takeoff power during the takeoff. The engine powerindicators had given false information to the crew, possibly due to ice blockingair inlet tubes which, in turn, sensed the power delivered. These tubes, whichhave an opening the size of a drinking straw, measure the pressure of air beingdrawn in by the engine compressors, and compare it to the pressure increase dueto combustion which is pushed out at the back of the engine. Known as PT2sensing tubes, they show the engine pressure ratio (EPR) on a cockpit gauge.(See CVR Transcript.)

Air Florida Flight 90In simple terms, if the front tube is blocked, the sensor thinks no air iscoming into the front of the engine. The rear sensor, operating normally, senseslots of high-pressure hot air being ejected from the tail pipe and thus the EPRwill indicate an abnormally high reading. The natural tendency to remedy theapparent excessive power indication on the EPR gauges is for the pilot to easethe throttles back in order to keep within perceived engine limits. The engineRPM gauge will, however, show the pilot the real power being produced.Obviously, if 100% RPM is indicated, the engine is really pushing out lots ofpower, regardless of a false reading on the EPR gauge caused by a blocked PT2tube. The advantage of the EPR gauge is that accurate power settings can bemeasured, providing of course that the system works as advertised.

Following the lengthy investigation into the Potomac accident, notices weresent to all operators of Pratt & Whitney JT8D series engines, warning thatcrews should be on alert for erroneous EPR indications in icing conditions andto rely primarily on the engine RPM gauge for actual indications of power.Typically, the RPM gauge is called an N1 or Fan gauge and will usually show 35%N1 while idling, 83% in cruise, and 95% – 101% on takeoff. Blocking of PT2tubes by substances other than ice was not discussed in the Alert Bulletin.

Boeing recommended that the crew calculate the expected EPR and N1 gaugereadings for each takeoff. These readings, which are placed on a takeoff datacard, will vary, depending on the takeoff weight of the aircraft, length ofrunway, ambient air temperature, and aerodrome pressure altitude. Also on thecard will be the V1 decision speed, rotation speed, and other informationpertaining to the takeoff.

An interesting situation

The following episode began when I was rostered to fly as a passenger on anonstop night flight to Guam in the Western Pacific. Flight time was four hoursand, on arrival at Guam in the early morning, I had planned to catch some sleepat The Hilton Hotel before crewing another flight to Manila.

There were 60 passengers including some deadhead crew on the flight and,after boarding, I settled into a first-class seat, adjusted my reading glasses,and watched the senior hostess brief her cabin crew as the engines were started.A few minutes later, at 0130 local time, the aircraft moved onto the runway,back-taxiing for takeoff to the northwest. From my window seat, I could see aline of cars on the nearby road only 50 yards from the runway. The flashing bluelight on a traffic policeman’s motorbike indicated that he had stopped alltraffic to prevent anyone getting blown off the road by the jet blast ontakeoff.

A few seconds later, the senior hostess came to me and said that the captainhad invited me up front for takeoff. Like most pilots, I welcomed the chance ofobserving the action from the cockpit and, leaving my reading glasses on theseat next to me, I entered the darkened flight deck, quickly sat on thejumpseat, and thanked the captain, whom I had trained for his command somemonths earlier.

The first officer was to carry out the takeoff and I caught the last part ofthe emergency briefing as we slowly turned to line up. The takeoff data cardindicated 10 degrees of flap for takeoff, V1 of 130 knots, VR (rotate) speed of135 knots, and initial climb speed of 145 knots. Even without reading glasses, Icould plainly see the EPR gauge digital cursors set for 2.18 EPR, which meantmaximum takeoff power was needed. This was understandable, considering the shortrunway, the hot night, and the extra fuel needed for a long flight. The datacard also showed that the crew had calculated 100% N1 was needed for takeoff,and this tied in with the 2.18 EPR limit. The N1 gauges were dimly lit and Icould not see the needles clearly without my glasses, which I had left back inthe cabin.

The traffic officer’s blue strobe light was still flickering on the roadahead and, from our position on the runway threshold, I could just make out thesurf of the Pacific a few feet behind us and the dark shape of the control towersome two thirds down the runway and just off the parallel main road. Fromprevious experience, I knew that the indicated airspeed should be around 120knots as the aircraft passed abeam the tower, with liftoff speed usually 10seconds later.

Takeoff power

The captain opened the throttles to 1.6 EPR with brakes set, checked thatboth engines spooled up evenly, then quickly advanced the throttles to theplanned takeoff power of 2.18 EPR. The brakes were released and the firstofficer began to steer the aircraft down the runway centerline. Accelerationappeared normal, and I could clearly see both EPR gauges steady at 2.18. Theairspeed indicator needle began to accelerate past 60 knots and I checked allengine gauges in a swift eye scan. Fuel flow, N1, and exhaust gas temperature (EGT)were all pointing in the right area, although somewhat blurred to my visionwithout my glasses. Seconds passed and the captain called “80 knots”as the dual airspeed indicator check. A sixth sense warned me that theacceleration was not the solid kick in the back that I would have expected from2.18 EPR, and at the same instant I noticed the captain begin to glance rapidlyfrom the instruments to the remaining runway ahead. There was no readilydiscernible problem but I had an uneasy feeling that something was not quiteright.

The company procedure was that, apart from the 80 knot airspeed check, nocalls were to be made by either pilot unless something was seriously amiss. Onthis occasion, the takeoff seemed to proceeding normally and, apart from myvague unease at the perceived lack of marked acceleration, I was unable topinpoint any impending problem.

The control tower and passenger terminal building flashed past the right wingtip, as I strained forward against my shoulder straps in an attempt to focusmore clearly on the vital N1 gauges. The EPR needles were clear – exactly 2.18,but again I could not get an accurate look at the N1 without glasses. Theairspeed reading went through 110 knots, we should have been perhaps 10 knotsfaster from my experience, and my unease grew stronger. One thing was happeningfor sure, and that was we were rapidly using up the remaining runway. Six runwaylights to go, and we were still at least 10 knots below V1, the go/stop decisionspeed. It was, to say the least, an interesting situation, and I hoped that thecaptain would not make a split-second decision to abort the takeoff because wecould now never pull up in time, even with maximum reverse thrust and braking.Our V1 speed was useless now, and the invisible sea swept rocks were onlyseconds ahead.

My unease had just changed into the cold realization that we were never goingto attain liftoff speed before reaching the end of the runway, when suddenly thecaptain urgently called “ROTATE NOW!” and while hauling back on thecontrol column he pushed both throttles hard against their forward stops. Boeingterms this “firewalling the thrust levers,” to be used as a lastresort to climb out of trouble.

The last runway light disappeared under us, as did a fleeting close-up sightof the brilliant blue flashing strobe light of a shocked traffic cop’smotorbike. I felt the reassuring surge of thrust propel the 737 upwards at adeck angle of 20 degrees, and silently thanked the Lord that the captain hadmade an instant correct decision to firewall those Pratt & Whitneys. I knewthat the Potomac accident might have been averted if the crew had only hit thethrottles wide open to the stops, to prevent their ice-laden Boeing fromstalling.

We were later told that the flight data recorder showed that the aircraft hadlifted off at 15 knots BELOW the calculated VR rotation speed, and that theaircraft had flown just 19 feet above the sea for several hundred yards beforegradually climbing away. We never did see the towering metal structure of thephosphate cantilevers that passed above our altitude, and situated 200 yards tothe right of the extended runway centerline…

What’s wrong with this picture?

Ahead was sheer blackness, and the captain locked on to instruments as theASI needle crept towards safe flap-retraction speed. The VSI was held at 1000fpm, and the first officer set the climb thrust at 1.93 EPR as the flaps wereslowly retracted in sequence. It seemed an abnormally long time before theaircraft reached 250 knots, which was the scheduled climb speed that night, andthe rate of climb was well below normal. Finally we passed 5,000 ft, engaged theautopilot, and called for coffee while we held a roundtable conference on therecent events. The mechanic who had been seated in the cabin came up front andsaid that a couple of deadheading pilots down the back sent their respects tothe captain, but they hoped he had finished playing silly buggers with theaircraft as they were hoping to get some shut eye! They had obviously felt thethrust change through the seat of their pants.

We turned our attention to a detailed scan of the engine instruments and themechanic remarked that the N1 indications seemed low when compared with the 1.93EPR climb setting. From the back of my mind came the recollections of previousproblems that I had experienced several months ago with an over-reading EPRgauge. On the first occasion, we had just attained takeoff thrust early in theroll, when one EPR needle moved to an apparent overboost figure of 2.35 EPR,while the second needle stayed steady at the planned 2.10 EPR. The other engineparameters were normal for takeoff and, in particular, both engines were turningup nicely at 100% N1. Clearly the problem was a faulty EPR indication and, asour speed was only 50 knots, I decided to reject the takeoff and return to theterminal for a chat with the mechanics. A check of the PT2 tube, plus an enginerun up, indicated the problem had cleared itself and we departed an hour later.

More recently, at 100 knots on takeoff, a similar fault occurred and thistime, the F/O urgently called that the engine was over speeding. He attempted topull back the throttle on that engine to limit the peak EPR, but I quicklystopped his hand and told him to ignore the faulty reading. He was convincedhowever, that the engine was overboosting because of the high EPR reading,although I felt no asymmetric yaw on the flight controls. I again prevented himfrom dragging the offending EPR back and we continued the takeoff using the N1RPM (which was steady at normal takeoff thrust). Once at a safe altitude, Iturned on the hot air bleed system to the engine anti-ice, and almostimmediately the offending EPR needle did a few cartwheels and returned tonormal. We were not in icing conditions but the hot air used for de-icing hadobviously cleared some obstruction in the PT2 tube. The flight was continuedwithout further incident.

Back now to the present situation, where early indications of long-distancestorm activity began to show up on the weather radar screen. The storm tops werearound 35,000 feet, and at our dismal rate of climb we would be in the thick ofthings in the next 20 minutes.

With the throttles set at the computed climb EPR, it was readily apparentthat both N1 readings of 88% and commensurate low fuel flows meant that somecommon denominator was affecting both engines at the same time. We discussedfuel contamination but decided that it was unlikely, given that the engines haddelivered maximum available overboost when the throttles had been firewalledearlier. I gave fleeting thought to the possibility of EPR gauge malfunction,especially after my previous experience with this problem, and knowledge of thePotomac accident. With a warm airport temperature of 30 degrees centigrade,icing of the PT2 tubes could be discounted and, in any case, it would be highlyunlikely that an identical malfunction would affect both PT2 tubessimultaneously.

On my suggestion, the captain momentarily switched on the engine anti-ice toboth engines. This would normally cause a small loss of about 5% N1 and an EPRdrop of .08, which reflected the stealing of some hot compressor air for pipingto the engine inlet cowls and PT2 tubes.

The N1 dropped obediently but both EPR gauges went crazy, increasing by anunheard of amount, and in the opposite direction to that expected. My mind wentback to a paragraph in the Potomac accident report which mentioned that with theengine anti-ice switched on and PT2 tube blocked, the EPR needle would indicatea reverse reading to that expected. Thus, tonight, the impossible had apparentlyoccurred: an identical erroneous reading on both EPR gauges at the same time.The PT2 tubes were obviously still blocked but we now knew for sure that bothengines were operating normally. The decision was made to return to land and, at500 feet, the landing lights were switched on, illuminating drifting mists ofphosphate dust from the nearby mine. The touchdown was perfect, right on the1000-foot runway marker. Well-coordinated reverse thrust and braking gave nicecool brakes on arrival back at the terminal.

Diagnosis

As the passengers disembarked to wait out the delay in the airport terminal,mechanics had already removed the engine nose cones in order to check out thePT2 system. With the aid of a flashlight, the cause of our troubles was soondiscovered. The PT2 tubes of both engines – the sensors that gave the vitalEngine Pressure Ratio readings for takeoff – were blocked, not with ice butwith congealed phosphate dust and some other glutinous substance. It wasimpossible to determine the precise time that the tubes became blocked, or howthe substance found its way into the system.

At dawn a few hours later, early workers driving past the departure end ofthe runway were the first to see debris from the coast road and nearby cliffface rocks, blasted back over the threshold by the jet efflux of the 737. Blackskid marks on the road showed where the traffic policeman had burned up rubberin a spectacular scramble for safety.

Later calculations showed that the actual power on takeoff was around 2.05EPR, even though the EPR needles were steady at 2.18. That power would have beenample for a long runway, and in fact was a setting frequently used for the rightcombination of runway length and gross takeoff weight. The N1 gauge scalebetween 91% and 100% is less than 3mm and very difficult to read in dim light,especially at a quick glance. This might explain why the crew was unable to pickthe apparent lower-than-normal N1 readings on the takeoff run. At nightespecially, it is also impossible to make any meaningful correlation betweenrate of acceleration and runway remaining. Until it is almost too late, that is.

Several months afterwards, I read a report that described an incident on aBoeing 727 that departed at night from a U.S. airport. The aircraft used 9000feet of runway and during rotation, it wiped out the ILS localizer antennasituated more than 1000 feet beyond the overrun area. The aircraft was damagedbut continued to fly. Investigation revealed that icing conditions had prevailedand the crew had failed to actuate the engine anti-ice switches for takeoff. Allthe PT2 tubes had iced up during the takeoff roll, giving significant EPR gaugeerror. The crew did not detect any acceleration problem until almost too lateand also did not firewall the throttles.

Later versions of the Boeing 737 have CFM56 engines which rely on N1 gaugesas the primary power indication. EPR gauges still remain on many older jettransports, however.

Aftermath

Following the incident on Nauru, the chief pilot suspended the captain fromflying duties. There was no in-depth investigation – only the personal opinionof the chief pilot. In his report to the President of Nauru, who also held theposition of Minister for Civil Aviation, the chief pilot recommended that thecaptain be downgraded to first officer permanently. This type of unilateralaction by the chief pilot was typical of the way he operated the airline, andthere was no effective avenue of appeal available to anyone unfortunate enoughto cross swords with the management pilots.

As I explained earlier, the phenomenon of unreliable EPR readings on takeoffhad occurred to me and other pilots, and although these had been reportedthrough official channels to management, there had been no revisions to theoperations manual warning of the specific problem. Some information had beencasually disseminated over beers at the bar of the local pub.

The Civil Aviation Department of Nauru consisted then of only twoindividuals: the Director and a Project Officer. Neither had aeronauticalexperience, both being more-or-less political appointees. Hence any advice onoperational matters was sought directly from the chief pilot, and his advice wasthen rubber-stamped. Operational surveillance of the airline was carried out bycivil aviation authorities from New Zealand. This meant that a flight operationsinspector from New Zealand would occasionally fly with a crew on a scheduledflight. Reports on flight crew performance were generally very good, althoughthere was sometimes mild criticism of the administration and support services.The maintenance of the aircraft was the responsibility of Air New Zealand, andthis really was first class in all respects. The government of Nauru spared noexpense in this regard.

When I heard that the captain had been demoted, I contacted the chief pilotto register a strong protest at this unfair action. The word had quickly gotaround the rest of the aircrew that the captain had been shafted, but apart froma few sullen mumbles out of the earshot of management, not one pilot had openlyquestioned the motives behind the management’s decision. Job security was thename of the game. The deputy chief pilot was a clone of his boss, and in facthad been the first person to meet the aircraft after its immediate return toNauru on the night of the incident.

Aware of the fact that someone is always the scapegoat in this type ofsituation, I had vacated the cockpit after landing, and was sitting innocentlyin a passenger seat when the deputy chief pilot boarded the aircraft on itsreturn. He was therefore unaware of my presence in the jump seat when the funand games had started. I had advised the captain to let me know if he needed mybacking as a witness, as knowing the then-management style, there was a strongchance that the captain would be pronounced guilty of a wrong operationaldecision without a fair trial. For this reason I wanted to keep my powder dryfor any forthcoming stoush.

In my view as a direct witness, the captain had done an excellent job ofairmanship in his decision to firewall the throttles. The chances of anidentical double EPR failure at night, causing identical instrument readings,were infinitesimally small, and it would be classically wise after the event toblame the crew for not picking the problem. The actual power (EPR) used on thatnight was similar to that used on an everyday reduced-thrust takeoff at longerrunways such as Hong Kong, Guam, Nandi or Sydney. The acceleration forces wereidentical to a planned reduced-thrust takeoff, and it was only at a late stageof the takeoff at Nauru that it was realized that the takeoff run was going tobe insufficient to lift off.

After the mechanics had dropped the engine cowls and discovered the blockedEPR tubes, I had been witness to an extraordinary outburst from the deputy chiefpilot directed towards the captain. He was told that the incident was all hisfault, and to get the aircraft on its way to Guam as soon as the mechanics hadsigned the paperwork.

On our arrival at Guam a few hours later, I was handed a message from Nauruthat I was to take over command of the return flight, and the other captainwould come home as a passenger. I suspected that the scene was being set up fora kangaroo court. Later events proved I was right.

A few days later I was home in Melbourne on days off, when I heard that thecaptain had been suspended indefinitely until the President of Nauru had made adecision to terminate the captain’s contract, or agree to the chief pilot’srecommendation to demote him for good. After connecting a tape recorder – I hadby now, little faith in justice – I telephoned the chief pilot in Nauru, andprotested strongly, stating that as an observer in the jumpseat, I thought thecaptain should have been congratulated for having done the right thing at a mostcritical time. The chief pilot warned me to keep out of the affair otherwise myown future would be at risk. I replied that I had no intention of closing myeyes to the matter, and that my report would go directly to the Minister forCivil Aviation. The battle lines were drawn.

Escalation

I contacted the New Zealand flight operations inspector responsible for AirNauru, and explained the circumstances of the incident. His name was Captain IanGemmel, himself a former chief pilot of Air New Zealand. Gemmel said he had onlysketchy details of the incident, gleaned from hangar talk by the Air New Zealandmechanics who had recently returned from Nauru from their fortnightly tour ofduty. He had not received any direct report from Air Nauru management, which ofcourse included the chief pilot.

I explained that I had been aboard the 737 at the time, and he listened withinterest to my side of the story. He was very diplomatic, and careful not togive any opinions on the telephone. I told him that the captain was undersuspension, but again he made no comment. When I suggested that he shouldinvestigate the incident in the light of his position as our flight operationsinspector, he replied that protocol dictated that he wait until invited by theNauru Director of Civil Aviation to come to Nauru. I knew that wouldn’t happen.

This was a dead-end conversation, but at least the inspector now knew thefacts, even though he could not (or would not) act to get a formal investigationunderway. Certainly he showed little interest in the fate of the captain. Thefirst officer, incidentally, was part of the management team drinking circle,and escaped with a minor admonishment quickly forgotten over the next round ofdrinks.

I next contacted Captain Belton, the then-Technical Director of theAustralian Federation of Air Pilots, known as the AFAP. Although Air Naurupilots could not belong to any industrial union by the terms of their contractwith Nauru, nevertheless the brotherhood of pilots meant that the AFAP wouldhelp with advice if sought. The captain and myself were interviewed by Belton,who showed great professional interest in the incident, especially with itsparallel in the fatal Potomac River B737 accident in the U.S. Ansett Airlinessubsequently advised their crews of the circumstances of the Air Nauru incident.

Belton then wrote to the Director of Civil Aviation (DCA) in Nauru expressingconcern at the treatment by management of the captain, stating that suchinjustice would never be tolerated in Australian airlines. He urged the DCA torelease the captain from suspension and initiate a full technical investigationof the incident. There was no reply from Nauru.

Politics

About that time, some hard decisions regarding the future of Air Nauru werebeing debated in the Nauruan parliament. The airline was heavily subsidized bythe government, and was losing money. The chief pilot was told to dismiss halfof the total pilot workforce, and it was left to his discretion who got thechop. About 15 pilots were given one week’s notice, although there were rumorsthat most of these would be rehired once the political crisis in parliament hadbeen resolved. The President of Nauru and his people were inordinately proud ofthe airline and its crews, and it had been with great reluctance that the orderto dump crews had been sent down the line.

In situations like this, it would normally be last-on-first-off in order ofseniority with the company. I thought I would be safe. I was dead wrong. Thechief pilot first got rid of all those captains over the age of 50, excepthimself. There were four of us, all senior in the airline. That neatly got ridof a few thorns in his side with no bloodshed. Next went a few more captains andfirst officers. One first officer had recently been recruited and hadvolunteered for the secondary appointment of navigation officer. His job was toupdate the office Jepp charts. He had only been in the airline for a few months,but kept his job because he had a formal “title.” He was also onexcellent terms with all the management captains.

Seniority or good service counted for nothing. One pilot sacked was thecaptain of the EPR incident. He was already on suspension anyway. While inlimbo, he spent a lot of money on a Boeing 727 command endorsement, and got ajob flying a 727 for a Saudia Prince. He went from success to success and at thetime of writing is a senior captain with a well-known Australian airline.

The crews dismissed were not told on what basis their names were chosen. Ibelieve it was a night of the long knives. A few weeks later, there was goodnews for some that were sacked, as Parliament authorized the rehiring ofeveryone, subject to the chief pilot’s choice. The knives were twisted when noneof the over-50s were hired, and were left to go on the dole in Australia. Soonafterwards, more pilots were hired to replace the over-50s that had been sacked,and first officers waiting in the wings were promoted in their place. There wereno airline jobs in Australia, and so I became a taxi driver, as did a fewothers. My most bitter moments were waiting for customers in a taxi rank outsideMelbourne airport to find that my clients were newly-recruited Air Nauru pilotshired to replace my colleagues and me.

Unfinished business

My last flight was a scheduled service from Nauru to Fiji and return.Attempts on my part to get justice for the suspended captain had foundered. TheNauruan DCA simply lacked the technical knowledge to adequately assess therecommendations by the chief pilot that the captain be demoted. They saw that asan internal matter between the captain and expatriate management. The captainwas dismissed as part of the sudden retrenchments, and the file closed. Therewas no follow up by the New Zealand Civil Aviation inspector because he wasnever invited for his opinion.

It was nighttime in Fiji as we loaded passengers for what was to be my lastflight with the company after 10 years of service. I was deep in thought as thefirst officer set up the navigation systems. I could hear the soft voice of theyoung Nauruan flight attendant as she welcomed her brood on board. The last ofthe passengers arrived at the bottom of the airstairs, and I noticed that one ofthem was a Nauruan cabinet minister whom I knew well. He had been the Directorof Civil Aviation when I first joined the airline all those years ago, and waswell regarded as a thorough gentleman. He was a qualified aeronautical engineer.

My own career with Air Nauru was to end with a final touchdown on Nauru infour hours time, but now I saw an opportunity to clear up some unfinishedbusiness. I was down the stairs in a flash, and greeting the minister like anold friend, I took him aside and asked him if he was aware of the near accidentto the 737 a few weeks earlier. He looked puzzled when I told him that therewere certain aspects of the incident which I didn’t like. He said Parliament hadbeen told by the Director of Civil Aviation that it was the captain’s fault, andthat the dismissal was warranted. Ink was now dry on the rubber stamp.

I invited the minister to the cockpit for takeoff, but meanwhile showed himthe tiny air intake in the front of the 737’s engines which had been blocked byunknown debris on the night of the incident. I showed with a flashlight that anyblockage would be undetected because of the curvature of the PT2 tubes. He wassurprised that the blockage of such a tiny tube could cause a near disaster.

After he boarded, the senior flight attendant closed the front door, andushered him to the cockpit. I asked him to bear with me while I gave him athumbnail sketch of the EPR gauge operation, and backed it up by showing him theschematic from the systems manual. All this time, the mechanics below werepatiently standing by to push the Boeing backward away from the airportterminal, prior to our starting the engines. We were already late on schedule,but I didn’t give a damn.

I explained to the minister that the incident to the 737 had importantramifications to future takeoff departures from Nauru, and that there was somesuspicion that the debris that had blocked the EPR tube contained phosphate dustfrom the island mines. I then gave him a notepad and pencil, and asked him torecord the various engine instrument readings on takeoff. I was hoping toconvince him that on a night takeoff with dim instrument lighting, it waspossible to misread the main RPM gauges by a small amount. That small amount hadproved critical on the night in question, and fatal on the Potomac accident.

As an aeronautical engineer, he was aware of my explanations, and as we laterlined up for takeoff, I told him to read the gauges at 80 knots and at liftoff.

I opened the throttles to full thrust and as the airspeed reached 80 knots Iasked the minister to take down the EPR, N1, and fuel flow readings. He asked meto turn up the instrument lighting, as he could not get an accurate reading. Atliftoff he again took the readings and complained that the N1 gauges (which givethe fan rotor speed in percent of RPM) were too hard to read at a quick glance.I then reduced the power to climb thrust and asked for a final reading of thethree engine parameters.

Next I asked the minister to adjust the throttle settings to variouspositions, and then asked him to call out the actual readings from the gauges.By now he had got the message that on takeoff, it took more that just ahalf-second glance to focus one’s eyes at night on the critical engine powerinstruments. With perhaps no more than three millimeters between a needleindicating 93 percent and 100 percent power, it was possible to miss acritically low power indication when the cockpit lighting was dim, as in adarkened cockpit. The situation where the main engine EPR digital readout wasfalsely displayed on the EPR gauge as full power only exacerbated the problem.

The aircraft was by now established on course for Nauru, and after engagingthe autopilot and double-checking that the ground-based navaids confirmed thatthe aircraft inertial navigation systems were tracking correctly, I switched offthe seat belt signs and asked the flight attendant to send up the coffee. Theminister sat quietly, his eyes scanning the cockpit levers and instruments andfinally settling on the green glow of the weather radar screen. A few areas ofheavy rain clouds were inching towards us from the top of the 180-mile markers,and I made a mental note to watch these radar echoes more closely in the nextten minutes. Our senior flight attendant, who was from the Solomon Islands,opened the cockpit door and delivered us three steaming cups of coffee. As sheclosed the door and returned to the bright lights of the passenger cabin, theminister said to me quietly, “Captain, what you are trying to tell me isthat you disagree with the opinion of the chief pilot in sacking the captain whohad the takeoff incident at Nauru?”

I chose my words carefully, as it was not my intention to come out with adirect criticism of the chief pilot. This would conflict with the island culturewhere it may be construed as poor manners to criticize one’s immediate superior,and any ill-chosen words could be counterproductive. I told the minister that hehad politics to contend with in his area of work, and that there was officepolitics in the flying and operational of the airline.

I pointed out to him that a similar event had occurred in Washington D.C.,where false engine readings, this time caused by ice blocking the engineinstrumentation, had caused the crash of Boeing 737 with many killed. The pilotshad failed to realize the cause of the problem until too late and the captainhad failed to firewall the throttles to power the 737 out of a stall. Thecaptain on the Air Nauru incident had acted quickly by advancing both throttlesto maximum available overboost and probably averted an otherwise-certainaccident. I added that there should be an independent technical investigation onthe incident, because as it was, the captain had, in the opinion of many AirNauru pilots, been unfairly dealt with by the chief pilot and others of themanagement.

“What do you want me to do?” asked the minister. I replied that thenormal procedure would be to formally advise the New Zealand Civil Aviationauthorities of the circumstances of the incident, and ask them to send aninspector to Nauru to interview the various people concerned. The ministeragreed to discuss the situation with his Cabinet colleagues. As I was about tobecome unemployed in three hours, there was no more I could do except hope thatthe minister would keep his word.

From gauges to radar

It was time to turn my attention to more immediate matters. The large cloudson the radar screen were growing closer, and their ominously red centers on theradar display indicated we would run into severe turbulence if the aircraftmaintained the direct track to Nauru. We were in thick cirrus cloud, which meantthat we were unable to visually navigate around the big stuff ahead, and werenow relying entirely on the radar to “see” the storms, and avoid them.

Over the years, the airline had experienced many failures of the radar, andseveral aircraft had inadvertently flown directly into severe thunderstormswithout any warning. Radar spares were held in New Zealand and Australia andcould take several days to finally reach the aircraft. Due sometimes tocommercial pressures, and occasionally a misplaced sense of the macho, therewere captains who would invariably accept the aircraft without a serviceableweather radar, and press on into the night risking thunderstorm penetration withall its well-known hazards to flight safety.

I had been a passenger on some of these occasions, and had been scaredwitless knowing that the radar was unserviceable. Passengers and flightattendants were always blissfully unaware of the possible menace ahead. Theweather forecasts around the Pacific almost always warned of the presence ofoccasional thunderstorms. Murphy’s Law dictated that one of these would haveyour name on it. Sod’s Law amplified Murphy’s which meant you could count on theprobability of blundering into a whole line of storms that were aligned withyour current track! There would be little warning until static electricity wouldstart to flicker in blue sparks over the windscreen, and next second there wouldbe savage buffeting and frightening turbulence. The knowledge that certain typesof thunderstorms could cause the destruction of an aircraft was ever in my mindon those occasions, because the aircraft was flying blind and the crew countingon statistics and luck to avoid the really bad storms.

The solution was easy, and that was to place radar spares at strategic portsaround the airline network. Guam and Nauru were the two hubs of our operations,but the various management teams closed their eyes to the problem, and insteadrelied upon captains to “cooperate” to keep the aircraft flying untilthe spares caught up.

With these thoughts in my mind, and the presence of a captive minister in thejump seat, I formulated a plan. If the plan was successful, it would mean asafer operation of the airline. Either way, I had nothing to lose, because myairline career was over – for the time being, that is.

The single thunderstorm (isolated, in meteorological terminology) was lessthan 50 miles ahead and we were closing on it at 7 miles a minute. That meant in7 minutes we were going to get beaten up by nature. Unless, of course, I steeredthe aircraft around it.

Hitting the stopwatch, I quickly briefed the first officer of my intentionsthrough the headset communication system, without the minister hearing theconversation. I then showed the minister how the radar controls worked, andexplained how to judge the severity of a storm by the various color codes on thescreen. I let him adjust the various radar control switches, adding that withoutthe radar we would not see the monster ahead. I then switched the radar tostandby, leaving a blank screen. The storm by now was 30 miles dead ahead, andinvisible to the three of us in the cockpit.

I told the minister that lack of suitable spares positioning around theairline network meant aircraft were occasionally flying without operating radarfor several days. We operated broadly by Australian Air Navigation Orders, whichrequired Australian-registered aircraft to have an unserviceable radar repairedat the next major servicing base, and in any case the aircraft must not beoperated in to areas where thunderstorms were forecast without a serviceableradar. I explained that there were many servicing bases in Australia, and anunserviceable radar was quickly replaced. This luxury was not available to ourcrews because of the far-flung nature of the Air Nauru route structure, coupledwith reluctance to hold spares at intermediate airports.

I had my eye on the stopwatch, with three minutes left before I would turnoff course to miss the storm cloud ahead. The minister began to sweat a little,as I explained that the blank screen in front of him represented anunserviceable weather radar, and could he not see the danger of flying blindwithout radar? Especially as we knew that there was indeed trouble ahead. Iexplained that this then was the dilemma facing the captains who were forcedinto the difficult choice of canceling a flight or accepting risks by keeping toschedule.

To avoid these situations, we needed to place radar spares on Nauru and Guam,I said. By now, the minister was getting tense, and so was the first officer.Both knew that the storm was almost upon us, and the minister hinted that it washigh time the radar was switched on. I asked him to do the honors, and in aflash he had switched the control knob from the standby position to on. Secondslater, a solid red mass bloomed at 15 miles, and I began to turn the 737 tostarboard using the autopilot controls.

Hardly had the aircraft straightened out on the new heading, when the cloudthat we were in magically disappeared and we were bathed in light from a fullmoon. Miles below there were hundreds of tiny cloud shadows on the Pacific, acharacteristic of this part of the ocean. There on our left a single monstrouscloud towering from the ocean to 35,000 feet slid silently past the wing intothe darkness behind us. Lightning flickered and flashed deep inside its core andI watched the face of the minister as he stared transfixed at the raw power ofnature.

“You have made your point, Captain,” he said. “Now where doyou want those radar spares?”

Partial victory

A few weeks later, I was driving a taxi. I heard through the grapevine thatthe New Zealand inspector had been invited to Nauru to investigate the takeoffincident. His report exonerated the captain, and recommended that he becommended for his actions in firewalling the throttles and thus preventing acertain disaster. The inspector also made critical comment on the lack ofoperational information in the company operations manual, following previousinstances of EPR tube blockage on takeoffs from Nauru.

The captain was not offered reinstatement despite the recommendations of theinspector, and ten years later he has still received no official commendationfor his actions.

Radar spares were allocated to be held on Nauru, but not on Guam. Ah well,you can’t win them all, I suppose!