24 September 2024

Thoughts on Varig flight 254

The vast majority of the YouTube and Reddit comments, Mentour Pilot’s video, and Admiral Cloudberg’s article are focused on the pilots’ errors in not realising that they were setting off in the wrong direction.

Only briefly mentioned is the fact that they were given the wrong heading, which to my mind should be considered almost the single cause of the accident. I don’t care what the airline’s policies were, we have ways of notating numbers and 0270 is “two hundred and seventy with a leading zero”, not “twenty-seven point zero”.

Corroborating this, from Wikipedia:

Months after the accident, the flight plan Varig 254 used was shown to 21 pilots of major airlines in the world during a test conducted by the International Federation of Air Line Pilots’ Associations. No fewer than 15 pilots committed the same mistake that the Varig flight 254 crew had made. After the flight 254 accident, Varig installed Omega navigation systems in their aircraft.

And the word “mistake” should really be in quotes there, as the real mistake was in the utterly absurd decision to notate decimal numbers without a decimal point.

Even putting the bad flight plan format aside, many commenters are baffled that the pilots managed to fly due west into the sunset without realising that this didn’t make sense given their destination, which was north-northeast of them.

I argue that this isn’t as unbelievable or unforgiveable as it might seem. Sure, pilots probably ought to have some basic situational awareness and sense of direction. But it takes mental effort to position and orient oneself accurately relative to map points, compass directions, and the sun, and to do so in an explicit enough way to notice an error like this. And I would bet that with the amount of automation and navigation aids pilots have access to, their minds will not be in the habit of going to such unnecessary metabolic expense at the start of every flight. They have enough other things to worry about, and the results of such mental calculations would almost always simply be less accurate versions of the numbers on the flight plan.

Further, pilots will fly in a wide range of different patterns, at different times of day and, for long haul flights, across time zones and hemispheres. Flights often take off and then make a sharp turn shortly thereafter. The position of the sun will therefore not be an easy to use indicator of general navigational status at all points in the flight, further encouraging pilots to tune it out. The important thing for them is to configure their aeroplane and nav systems correctly, which by any sane interpretation of 0270, they did.

With the very reasonable assumption that they had been flying in the right general direction, it is completely understandable that they became confused and disoriented when they appeared to have overflown their destination. The decisions that followed, such as not flying to a high altitude and asking for help as soon as they realised they were lost—and the lack of CRM—were bad. But the original navigation error is a strong mitigating factor here, not an aggravating one.