Originally Posted by
Major G
While all the talk of jet blast is interesting, I doubt it is why the towed in my plane at SFO. Tight turning radius dictates using a mechanical means to shorten the turn radius (i.e. using a tug).
Doubt it all you want, but the primary reason is to avoid the jet blast at gate 79. The UAX aircraft positioned at gate 79 is parked directly aft and to the left of any plane at gate 80. When pulling into gate 80, because of the angled turn in, pilots have to apply assymetrical power (high N1 on the left side engines). Because of this technique, there have been prior incidents of Foriegn Object Damage to aircraft parked at gate 79. The associated risk to customers, airport personnel and equipment mandate that large aircraft arriving gate 80 are towed-in.
Originally Posted by
Major G
Think of it like this, no matter how far you crank your car's wheels you still move forward in a radius when turning. Now if you got a jack under your front wheels, you could pull the font end in a perpindicular direction, turning the car in a radius based upon the rear wheels.
For the aircraft in question (primarily anything larger than an Airbus 320), they are towed into the gate using a tow bar. The wheels are not "jacked" and pulled in a perpendicular direction. The nose gear are limited to the number of degrees from center that they can be manipulated without causing damage. Instead, using a tug the aircraft is pulled into position in the exact same path as if it had been taxied into the gate.
Originally Posted by
Major G
Likely, at that gate it is too difficult for the jet to make the radius required to clear the jetway and finish in the posiiton required for passenger loading. Therefore, they use the tug to turn the jet and bring it in.
The only truth you present is that it is too difficult for the aircraft to make the required turns without risking collision with the terminal or with an aircraft parked at gate 79. Therefore, a tug is used to tow it in so they have more control.