The recent taxi accident between an Airbus A-380 and a regional jet at JFK serves as a reminder that taxiing our aircraft can be a dangerous endeavor. Just think about the potential of all that fuel in the wing of the A-380 had it been ruptured. Now I don’t know where the A-380 was in relation to the center line that night but I bet that Captain hopes that the investigation indicates he was right on it.
We don’t yet know the cause of this accident and I am not taking sides, but I do have compassion for that Airbus Captain, because taxiing a wide body aircraft at night in the rain is in my view a lot more difficult than landing the plane.
One alleged expert was quoted on a news program as saying the problem with the new airplanes is that the winglets obscure the pilot’s vision while taxiing. Sadly, this expert has apparently never taxied a wide body airplane.
While I have never taxied an A-380, I have a lot of taxi time in a Boeing 747 and I can confirm that learning to taxi the airplane safely presented a big challenge and was the subject of considerable training. Since all the wheels and most of the airplane are well behind the pilot and he can’t see any of it he needs to learn other cues. Newer airplanes like the A-380 do have remote cameras that I am sure help a lot but it is still no picnic.
First of all, the winglets have no bearing on what a pilot can see because it is impossible to see the wing tip as it is way – way behind the pilot. In light airplanes our sense of ground speed during taxi is influenced by our experience driving a car since we are about at the same height when performing both tasks, not so in a 747. The pilot is about three stories above the taxi way and that creates the illusion that you are taxiing very slowly when in fact you may be going too fast. Further being that high makes the taxi way look like a very narrow driveway. The good news is that nobody blocks your view.
Now consider that the nose wheel is 25 feet behind the pilot and you can see that keeping the pilot on the centerline during ninety degree turns will put the wheels in the mud. Approaching a ninety degree turn you have to extend your nose well beyond the edge of the taxi way and out over the grass before you start the turn. If you have done everything correctly, your main gear which is 114 feet behind the nose of the airplane will come around the corner OK. No cutting corners in a 747.
On the straight away staying on the center line is also a must, since the main gear takes up 42 feet of the 75 foot wide taxi way there is little room to drift. In addition, you have to be alert for obstructions to the side because even though you cannot see them, all four engine are over the grass beyond the edge of the taxi way.
Doing a 180 degree turn takes a lot of room. If everything works perfectly and you turn at the maximum rate, the main gear uses up 153 feet of the runway, but the outboard wing tip carves an arc of approximately 222 feet. Lots to hit with a swing like that.
So what does this have to do with us taxiing our smaller GA airplanes and staying on the center line? First we carry most of our fuel in the wings, so hitting something with a wing can still cause serious problems. Second, it is hard to blame someone other than the pilot for a taxi accident.
So if it happens to me, I want to be able to say I was on the center line at the time of the accident.