GUEST EDITORIAL. In the aftermath of the recent mid-air in India between an IL-76 and an opposite-direction B-747 flying the same airway, the authors suggest that pilots might well use the remarkable accuracy of today's modern GPS or IRS/INS navigation gear to enhance safety by flying a mile or two to the right of centerline. Although their comments are aimed primarily at international airline operations under IFR, the idea would seem to have equal merit for general aviation pilots and VFR operations.
February 19, 1997
The recent mid-air between a Kazahk IL-76 and a Saudia Boeing 747 near New Delhi highlights a concern
which we have been discussing between ourselves for months. While all the details may not apply; this
disaster does dramatically illustrate our concern.
The modern onboard GPS and/or DME-updated IRS/INS navigational equipment has greatly enhanced the
ease and accuracy of aircraft navigation. However, under certain circumstances, this accuracy could become
a flight safety hazard. Airline pilots spent untold hours EXACTLY in the center of their 10 mile wide airways
guaranteed only 1,000 or 2,000 feet vertical separation from opposite direction traffic. If there is a mistake
during an altitude change by the crew of either aircraft, by the controller, with the communication between
the two, or an autoflight equipment failure a disaster may occur.
As international airline pilots, we spend hours and hours cruising over continents like India, China, Russia
and other places where the communication could be improved (to say the least!) and the opposite-direction
traffic often has no TCAS, sometimes no transponder, and might be using a slide-rule to convert altitude
assignments from feet to meters or altimeter settings from inches to millibars. With that in mind, it is
frightening to see the accuracy of today's on-board navigation-systems with opposite-direction traffic. In the
old days (before the advent of GPS and DME-updated IRS/INS), you could spot this traffic somewhere left
or right of your own track. But these days there is no more "left or right" the traffic is almost always right
on the nose.
But there's a simple, commonsense solution. Something we use every day when we drive to the airport. Fly
FMS navigation computers should be offset just one or two miles to the right of track. This would guarantee
2 to 4 miles lateral separation between opposite direction traffic while all aircraft would still remain well
within airways. This would utilize the extreme accuracy of onboard navigational systems to both remain
within airways and to provide additional traffic separation.
Had both aircraft been equipped with TCAS, the New Delhi disaster would probably have been prevented.
Unfortunately, all aircraft world-wide are not so equipped. [Even in the U.S., most jet freighters don't
have TCAS. Ed.] But even the simplest aircraft can fly a mile or two right of centerline.
Airline pilots almost daily will pass another aircraft with this 1,000 feet clearance. Wouldn't it be much safer
to also have at least two miles lateral separation? Since equipment and people do fail, why not implement
this fail-safe technique?