Ask Captain Lim ~ All about Aviation

Hi Capt Lim,

I just read about the Brazilian Boeing 737-800 crash in the Amazon. I will be flying myself in December and it*s quite a scare to read the possibility of airliners colliding in mid-air. These are two very modernized airplanes (Boeing 737-800 and Embraer Legacy 600).

My questions to you are:

Does a smaller aircraft stabilize better than a larger one in the event of a mid-air problem?

In this case, if it is true indeed that the aircraft might have clipped each other, the Boeing 737-800 could not stabilize while the smaller Legacy 600 was able to. Could this be a reason why the 737 crashed and the Legacy did not?

Also, I was wondering, how long is an aircraft allowed to operate before it is considered worn-out? I just always wonder how long the engines last and how do they determine when it is time for an airplane to be grounded due to too many flying hours?

I just came across your site after I googled *flying safety* and I have to admit that your advice helps a great deal in understanding the safety of flying and what it really takes for millions of people to criss-cross the Continents.

Thanks so much Lim.

Steven Koskei.
Department of Environmental Sciences.
West Texas A&M University.

Hi Steven,

All airplanes are designed to be stable even though they are constantly being subjected to the various forces that disturbed them from their normal horizontal flight path. Whether a smaller airplane would stabilize better than a larger one in the Boeing 737-800/Lagacy 600 mid-air collision, one would have to look at the circumstances of the case.

Right now, the complete story is not very clear. Brazil*s Federal Aviation Authority stated that it was still impossible to confirm whether there was any relation between the incident that caused the Legacy 600 crew to perform an emergency landing and the Gol*s Boeing 737-800 to crash. But there were suggestion that the private jet, apparently piloted by an American, had in fact hit the Boeing 737-800.

If it were true, the question is: How was it possible for two ultramodern aircraft with the latest anti-collision equipment fail to prevent the disaster? I believe, the official investigation report will come out with an answer in the end (how long?).

Meanwhile, it was reported that the executive jet was able to land even though it suffered a wing damage. Does it mean that the Lagacy 600 is more stable? It is not necessary so. A lot would depend on the extent of the damage during the collision.

Remember, both these planes have winglets. Flying with one winglet sheared off is not an impossibility. Looking at this hypothetical scenario: if one of the executive jet winglet were to strike the elevator of the Boeing 737-800 from below, then it can cause the bigger plane to lose control. What happen if it were the other way round? Probably the consequences would be different. :-(

For your other query on how long is an aircraft allowed to operate before it is considered worn-out, please read my answers in "Are older planes less reliable?" and "How many cycles can a fuselage withstand the extreme condition it flies in?" in previous FAQ.