Hi Y'all,

Powerbacks are very common here at DFW (and standard thru the AA system).

The rolling forward at the start is to getthe plane off the "flat spots" on the tires. Aircraft tire aren't pumped up to a high pressure (heat from braking causes the air...actually nitrogen mix...inside to heat and expand; need low pressurre to allow for expansion). Therefore, while sitting at the gate, the weight of the plane causies the tire to get "out of round". It's preferred to go forward to get off the flat spot cuz too much power in reverse is bad...it throws all the debris into the front of the engine only to get sucked up and cause possible damage.

Eastern used to powerback 757s. AA did on their 1st 757 flight (DFW to SNA..Orange County CA) but it needed so much power that they immediately suspended future 757 powerbacks.

Tail mounted engines on 727, DC-10s etc do have thrust reversers.

Steve