Is there a difference (i.e. from all other airlines, and regardless of type or aircraft) in takeoff and departure procedures for Northwest flights departing northbound at Reagan National takeoffs? Why and why would FAA approve such a difference in application of noise abatement procedures?
Two aspects: (1) NW pilots use more runway, or at least rotate closer to the end of the runway, and (2) NW left turnout departures going north up the Potomac use a much more gradual slope than that employed by all other pilots and airlines.
When I lived just up the river from DCA in Rosslyn in the late '60s and early '70s, I could always tell a NW departure, then typically a 727. They simply came over Rosslyn much lower than anyone else.
Just today, watching takeoffs at the north end of the main DCA runway, any NW flight lifted off much closer to the end of the runway than flights for all other airlines. And, they followed a slope perceptibly less steep than that for planes of any other airline. [a 319 to DTW and a 320 to MSP]
Anyone confirm this? If so, why is NW so different?
NWA may be using more aggressive deratings for takeoff and climb thrust than other airlines. Derated (or flexible) takeoff/climb thrust (producing less thrust than the maximum that the engine can produce) reduces wear and tear on the engine and may save a bit on fuel burn. They could also be heavier with passengers and cargo, or both heavy loads and aggressive thrust derates.
I agree that flex takeoffs are a good possibility. We use them on the G2 regularly, the only difference is that we start out overpowered and a heavy 727 is underpowered to start with!
If you are wondering flex calculations still take into account runway length, accelerate-stop, accelerate-go, and required climb gradients. They save fuel, noise and reduce engine overhaul costs. So the bean counters say. 8)
Consider this - Aircraft can come off the Potomac river and vectored on course leaving 3000 ft. A steep climb would benefit most departures destined for airports to the south and east over the FAK, GVE, LDN, SWANN or PALEO departue fixes.
Northwest, on the other hand almost excusively departs to the NW fixes of BUFFR and JERES because that is where their route structure is (DTW and MSP). That being the case, NWA has no real incentive to get off the river or off the DCA328R or get out of 3000 ft. quickly because they will need to go out to the vicinty of the American Legion bridge 10 miles to the NW before being vetored on course. I would assume that a quieter more efficient climbout is perfect for them.
