Guest Blog: Why Helicopters Get Away With Running Scud


The recent Kobe Bryant accident in low-visibility conditions and the many others like it always elicit comments similar to, “What is a helicopter doing flying in IFR weather like that?” The short answer is because they can. Flippant, but true. By and large, fixed-wing aircraft are stable platforms. Trim them up, release the controls, and they tend to stay in whichever attitude they’ve been placed. If momentarily forced into another attitude, most will return closely to the original placement.

On the other hand, without some sort of stability augmentation, many helicopters do not have that luxury. While the collective remains relatively trustworthy, the cyclic (stick) has a mind of its own. Take your hand off of it, and the cyclic will try to find the shortest way to the floorboards, which can lead to uncommanded unusual attitudes and startled exclamations.  

Short of an autopilot, various methods have been used to tame the cyclic, from introducing a friction arrangement similar in result to that employed in throttle quadrants to magnetic clamps that operate by pinning the cyclic in whichever position existed at the moment of activation. Without some sort of augmentation to provide some stability, the shortfalls of these sorts of fixes are obvious. But they do allow you to take your hand off the cyclic for short periods.

However, helicopters do have a redeeming feature: They can fly slowly and safely close to the ground and that quality is an important difference between fixed-wing and rotary-wing flight. That capability will give you time/distance to see something and react to it. Recognition of that capability is reflected in the weather limits approved for each type of aircraft and for helicopters. This has evolved into rules very different than those applied to airplanes and fixed-wing pilots don’t always understand why.

It has to do with recognizing threats and reacting to them. So, how much time/distance is needed to perceive a threat, process it, formulate a plan, and execute the plan? While many of us think that we’re at the top of our game and that we can swiftly process information and reach a solution near instantaneously, the reality is that it takes time and space. The time interval will be dependent on your proficiency level and your comfort level in that environment, but let’s pick 30 seconds as a representative figure. While time/space should be equal, many fixed-wing pilots will also have a minimum visibility distance at which they feel comfortable for a given altitude/speed.

For instance, given no obstacles or restriction to vision, most fixed-wing pilots would quite happily fly all day at 500 or 1000 feet above ground level at cruise speed of 120 knots or more.  However, drop the visibility to three miles in haze/fog, and the same pilots will be thinking about reducing speed. Drop visibility to two miles, and most pilots will have reduced speed and voluntarily/involuntarily reduced altitude to maintain good ground contact. Drop the visibility to one mile, and if not already there, the pilot has probably reduced altitude to around 500 AGL and further reduced speed; possibly to 90 knots or less.    

Now is the time that the prudent fixed-wing pilot should carefully consider his/her options: The required 30 seconds reaction time equates to about 2100 lateral feet—well within the visibility limit. But going any slower and/or selecting flap will mean giving up maneuvering capability and may well encroach upon the distance necessary for the aircraft to turn away before overrunning the threat. In any event, visibilities below one mile are now probably well outside the pilot’s comfort level even at reduced speeds. It is like night driving in moose country; there is a point at which you’re overdriving your lights and you know you’ve given up reaction time.  

It’s at this point that the helicopter comes into its own. Due to its unique ability to reduce speed quickly, the helicopter can easily maintain cruise speeds even in one mile visibility; reaction time is the only concern now. Thirty seconds at 120 knots equates to 3000 feet, still well within the one mile visibility available. (Note: I’m using knots for speed and statute miles for visibility, which is how it is reported.)

If the visibility drops to further to, say, 3/4 mile, the helicopter can maintain/reduce speed as necessary and reduce altitude as required to maintain good ground contact. Even at 90 knots, the required 30-second reaction time is still just over 2000 feet and still well within the visibility limits. If the visibility drops further to a half mile, the helicopter reduces altitude as required and adjusts speed commensurately. Anything between 60 and 90 knots would suffice. Even at 90 knots, the pilot still has twice as much distance required for reaction time.  As the visibility further reduces to ¼ mile, the pilot will—or should—slowly reduce speed to 20 to 40 knots as he reduces altitude to maintain good ground contact.  At these speeds, the required reaction time reduces to near zero; the helicopter can be brought to a standstill or landed in seconds.

Further reductions in visibility will result in further reductions in altitude and airspeed until the helicopter is moving at a walking pace at hover altitude or is on the ground. During this time, the helicopter has been in visual meteorological conditions (VMC) the entire time and that is the crux of rotary-wing flight in these types of conditions. The key principle is when you go down, you slow down. This inextricably links threat assessment and reaction time.

And that is why helicopters have different limits than fixed-wing aircraft. That is why a helicopter can legally fly in weather conditions of one-half mile/clear of cloud on the one hand and get an IFR clearance to fly SVFR clear of cloud with visibility less than a mile on the other. The helicopter has the ability to slow down, winkle along, and stop/land if necessary. Whether on a SVFR clearance or operating outside controlled airspace, rotary-wing aircraft easily maneuver in VMC conditions unsuitable for fixed-wing aircraft.

Now, every now and then, you’ll hear of a flying machine that wound up in cloud with disastrous results; the cause: inadvertent IFR or VFR into IMC. However, that statement is a misnomer. There is no such thing as “unintended” or “inadvertent” IFR. Most pilots who encountered it knew for minutes or miles that such a thing was possible. It should really be called “advertent IFR.”

That’s the reason for the saying in the helicopter world that if weather forces you go down, you slow down. Even so, there is always the distinct possibility that you may run into trouble before you have time to react; that is, you go from one mile in fog to zero-zero in cloud. Even if all precautions are taken, there’s always the possibility that ground contact could be lost and you have to quickly react.

To paraphrase Jack Nicholson: “If you’re going to dance with the devil in the pale moonlight,” you’ve got to have a plan B. Therefore, if you’re low level, say, 500 to 1000 feet, in reduced visibility at cruise speed and enter IMC conditions, you go on the dials, note your heading, note the reciprocal and then make a level, 180-degree turn toward the low ground and fly back into better conditions.

If you’ve already been operating in reduced visibility, make a climbing, 180-degree turn toward the low ground until terrain clearance is assured. If you’re in hilly or mountainous country, then you pick a heading that will keep you clear of terrain until you’re at a safe altitude and then turn towards better conditions. Synthetic vision (as I have in my aircraft) is very handy for that.

Now, the foregoing is not some theoretical, academic treatment of the subject of operating in low visibility conditions, but is the result of the experience gained from over a 40-year fixed-wing/25-year rotary-wing working career of which 15 of those years were spent working for a company with a mixed fleet of aircraft and routinely switching back and forth between types, often on a daily basis. 

It is not a recommendation what a pilot should do in a given situation, but what the helicopter can do in that situation. It is concerned solely with the capabilities of each type and shows that the helicopter has a unique ability, a capability that is recognized through regulation accommodation.

And that’s why helicopters often operate in weather that alarms pilots of fixed-wing aircraft.

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  1. Yip, and it is also an illustration of how tech has changed things since the late 1970s.
    Then it was hopeless calling for a chopper on a dark, moonless night, no matter how bright the stars were.
    Helicopter pilots need to see a horizon or they crash was the explanation.
    Then heavy night vision helmets were developed which gave them a horizon at night — albeit a fuzzy green thing guaranteed to give splitting headaches and neck aches which 20 years on, some claim have never gone away.
    Now artificial horizons and other gizmos mean they can take off into near zero visibility, fly across nasty seas in howling gales with everything that is not black being grey, and then land on a heaving platform to deliver chips for the fryer. That is progress for you.

  2. And there it is again… the 180 turn around. I know this has been taught for at least the 40 years I’ve been flying. It is WRONG. In fact the FAA helicopter hand book has been changed. I’m not sure if the fixed wing handbook has been changed. Do not do this ‘180’ turn around if you enter the clouds. It will kill you. The action of turning your aircraft (fixed wing or helicopter) while going IIMC is the perfect condition for vertigo. Do your 180 BEFORE you get into the clouds, NOT AFTER. Do not turn if you go IIMC. Level the aircraft wings and remain level for at least 90 seconds as you adjust to instrument flying. Squawk 7700, yes, you screwed up and you need help. This will get the attention you need from ATC without talking. You will not have to worry about hitting another plane with the 7700 code, unless someone else is out there scud running too. You may think ATC doesn’t know you are in the clouds, they likely suspect it already. They can not stop you from killing yourself. They will try to help you, not kill yourself. Call them for help. Only climb if the terrain you were heading toward requires it. Remember, DO NOT TURN. You will only get lost and confused as to your location. Hopefully you knew where you were and where you were going, before you went into the clouds. Turn and you will not know where you are or where you are going… this will bring on confusion and more problems. If the controller ADVISES you to turn (remember this is an EMERGENCY, ATC is just advising you at this point) only make half standard turns and only if you don’t have the leans (vertigo). If you don’t feel good turning, don’t. Keep wings level and only if heading toward terrain, make a ‘slow’ climb. After a few minutes you will get use to the instruments, and can try turning again. Only turn if you feel comfortable. ATC turns are advisory during an EMERGENCY. They want to help, and in most cases will help. They don’t want you to die.

    So, here it is in an article. The 180 turn that kills. I’m sure this guy is a good pilot, but this article deadly advise.

    • It would seem a 180 turn would be especially risky in a helicopter without SAS, given how unstable a helicopter is. If there is ground below you, it would seem a descent straight ahead would be safest bet.

      • For some reason I remember being told this in my training many years ago. It never sat well with me. Trying to do a precision instrument flight maneuver without instruments set, or being mentally ready for instrument flying, doesn’t even sound rational.

        • I agree. It’s bad enough in a stable aircraft, but seems like even worse of an idea in a helicopter.

  3. Yah, but helicopters like the B206 and S76 can fly at 150 knots to get home faster. (gethomeitis facilitator)

    Though flying quite close to the ground in a single-engined machine is dicey?

  4. Good article John. It is not the weather (or moonlight) that kills pilots in either type of aircraft, it is pilot decisions that kill. Human Factors kill, and their are a bunch of those to be concerned with. Ego, over-confidence, the need to succeed, the need to complete the “mission”, the need for money, the need to be recognized etc, etc, etc. CRM , plus veto power at all levels, fixed (well mostly fixed) the accident problem for 121. SRM, ADM, and more regulations will not fix the human factors accidents for 91 and 135 ops, especially single pilot ops. System Safety programs at the 91 and 135 levels are only as good as the managers and most of those managers have financial influences guiding their decisions. The Colgan accident at KBUF was the wake-up call for 121. What will it take for 91 and 135 to wake up? We already know that 10 more Kobe accidents won’t change the trajectory for GA.

  5. Helicopters should stay away from any airport with fixed wing aircraft unless they operate by the same rules. These helicopter pilots are rude.

    • Actually, the rules require helicopters to avoid fixed wing traffic. They should be using opposite traffic. If the fixed wing are using left traffic, helicopters should be using right traffic.
      Not everyone can land on a dime when learning to fly helicopters. When coming down they usually want a runway to practice auto rotations in case something goes wrong and they do need to put it down. That is why they are equipped with shoes that scrap along the runway… it makes my skin crawl when I hear the scraping. It doesn’t sound natural for any aircraft to make that noise.
      But, in some cases it is the only safe way to land or take off (I would never take off like this, but some do at high density altitudes)
      So, yes, they should be avoiding airplanes. I do use taxiways to air taxi, only to make sure the controllers know where I am. Oddly, something I noticed controllers will do, is clear a helicopter past more than one active runway at a time. This is because, technically, the helicopter is ‘flying’ past the runways and not ground taxiing. It was odd the first few times, and I always looked twice and rechecked with the tower before crossing the flight path of a parallel runway.

  6. “Thirty seconds at 120 knots equates to 3000 feet…”

    I’m not arguing against your premise, merely the fact that your calculations of distance traveled over time at a particular speed are inaccurate.

    Basically, 60 knots is by definition 60 nautical miles per hour, or 1 nautical mile per minute.

    Therefore, 120 knots is 2 nautical miles per minute, or 1 nautical mile per 30 seconds.

    One nautical mile is equal to 6,076.12 feet (imperial units).

    Thus, traveling for 30 seconds at 120 knots equates to a lateral distance traveled of 6,076 feet, or 1.15 statute miles.

    And the distance traveled in 30 seconds at 90 knots is a lateral 4,557 feet, or .86 statute miles.

  7. 120 is much too fast in low visibility. Slow down to half of that or less. There was no reason for the Bryant helicopter to be going as fast as it was. Do not expect to be able to slow down rapidly as the article implies you can in a helicopter but instead slow in advance so you are not reacting but instead have plenty of time and space to observe and plan.

    Scud and poor visibility flying is reality for helicopter and it is not to be avoided but instead managed with good training, planning, and pilot proficiency. Do not count on help from ATC as often they are not even covering where you have to go. Do not expect TAWS, CVR or any other device to save you. If you have 4 axis autopilot, great, use it but also have the skills to back it up. There are ways to learn to manage scud and to develop solid proficiency for instrument flight.

    Always have an out.

  8. As for “rude” helicopter pilots much misunderstanding exists between airplane and helicopter pilots. The best advice for both is to read and know the procedures in the AIM as they are well thought out and honed through experience. The sad reality is most pilots do not know what is in there nor do they take the time to find out instead expecting others to behave as they wish rather than according to established methods.

    To helicopter pilots I would say do not argue or fight as this can happen easily. I have been met by very angry people who had no clue and threatened with violence for following documented procedures. These people exist in every walk of life not just aviation. Let them be and fly on.

    To all I say be tolerant and keep yourselves in check. How do you know the other person intended to offend you? Perhaps they are a student learning and making a mistake or a new inexperienced pilot. Always try to be sympathetic and find out before complaining or becoming hysterical. After all if your emotions can get you so easily upset how do you think you would stay together in a real emergency or hazardous situation?

    • As a still-fairly-new fixed-wing convert to helicopters, I only recently (in the past 3 years) learned about the differing rules for helicopters. Unfortunately, the fixed-wing training world doesn’t provide much information on helicopters other than “yeah, they’re different”, so it’s no wonder that fixed-wing pilots think helicopter pilots are breaking all the rules and getting away with it, when the reality is that they’re exactly following the rules. I’m still getting used to being able to use taxiways as “runways”, or even ignoring runways all together and just taking off from present position on whatever heading I wish to depart.

  9. Since the 180 degree turn is generally initiated in an attempt to “get back to VFR”, perhaps in many cases the best default decision is to instead accept you are now IFR-committed and ease the transition from VFR by climbing straight ahead until you get things sorted out both in the cockpit and with ATC.

    This assumes, of course, you have enough situational awareness to know the terrain ahead will permit such a climb. Given these things so often happen when attempting a scud run though a known pass, that will often be the case.

  10. One major item that has left out of the discussion is that the helicopter has the capability of landing safely under most circumstances.