Quote:
Originally Posted by Lessu
Yes, very nice video. It made me google touch and go landing though as I was wondering why anyone would need to do one in practice.
I read the wikipedia article about it and it mentiones a debate about its use even when teaching a student.
So I guess I can assume that there is no situation on a commercial flight where you would ever need to touch and go? Or have you done one?
Your assumption is correct. We are not trained to do touch and goes and it is not an authorized maneuver. First of all, there is no need for them in normal operations and, secondly, we have no performance data for them. The only time it could conceivably occur in a passenger carrying commercial flight is if the Captain exercised his emergency authority and did it in the interest of safety; i.e. the alternative (completing the landing and rollout) would put the plane in immediate peril.
Here's one scenario: the plane touches down and a 747 ahead doesn't hold short as instructed and begins to taxi across the runway 2000 feet ahead of the landing plane (this is called a "runway incursion" in the biz). Your choice: collide with the 747 or take off again. The Captain can throw the rulebook out the window in an emergency. The only catch is he has to be able to justify it later.
There was a day when touch and goes
were used by airlines, but only for training. This was before the advent of modern Level D simulators, which can be used for all the training necessary for a type rating. Before these sims were around, much of the training took place in the airplane (including simulated engine-out emergencies in which the instructor would pull one engine to idle thrust).
I remember seeing TWA fly a B-747 around the pattern at Dulles Airport in the 70's. Back in those days Dulles was a virtual ghost town...perfect for doing some practice "bounces." After touching down, they'd set the flaps and trim for takeoff and apply the power, then pull up to an incredibly high deck angle (lots of extra power on an empty 747) and bring it back around.
Tough and goes are used routinely in light airplane training for the simple reason that it is an efficient way to get more landings per hour. With the cost of a C-172 in the $125/hour range, it gets expensive to land and taxi back for each landing. Aircraft performance is not as much of an issue with light airplanes as the runway is often long enough to land and come to a complete stop before applying power for another takeoff. "Taking it on the roll" (i.e. applying power right after touching down) can be done safely and is very attractive when you're stroking those checks for the rental time.
I sometimes go to the airport to remain current in light aircraft and I've done my required three takeoffs and landings in as little as 0.3 hours (as measured on the Hobbs meter in the plane). If I taxied back for each of these landings, it would probably be twice that.