Quoting Morvious (Reply 61):
Isn't it so in the -400 that if you don't have a minimum of flaps 10 set for takeoff, you will hear a warning sound in the cockpit when adding power over 70% N1? |
That's absolutely correct. On a B744, if the following conditions are not met (while the airspeed less than V1, three or more fuel cutoff switches in the "run" position and commanded thrust on the #2 or #3 engine is advanced to the takeoff range), the aural takeoff configuration warning will sound, along with a "TAKEOFF CONFIG" message on EICAS and a master warning lights will illuminate:
CONFIG FLAPS - flaps not in takeoff configuration ("10" or "20")
CONFIG GEAR CTR - body landing gear not centered
CONFIG PARK BRK - parking brake is set
CONFIG SPOILERS - speed brake lever not in "down" position
CONFIG STAB - stabilizer trim not in takeoff range
Nearly all other commercial jetliners that I am familiar with have a similar warning system.
But as the story below highlights, warning horns don't always work:
Quoting FlyNYC (Reply 38):
31 Aug 1999; LV-WRZ, 737-200C, 20389/251, Del 17/4/70, LAPA; Buenos Aires, Argentina:
The aircraft settled back onto the runway just after takeoff, overran the runway, hit two cars on a nearby road, and caught fire. The crew had not selected take-off flap and had continued the takeoff despite the take-off configuration warning horn sounding for the entire 37 second take-off run. There were 65 fatalities among the 98 passengers and five crew members. Two of the occupants in the cars were also killed. |
As it has often been mentioned, the B744 is physically able to takeoff without an lift devices deployed, given enough runway length and a total disregard for the maximum landing gear wheel speed (a speed that prevents the tire from separating due to the centrifugal forces of rotating at extreme speeds).
However, I think that the fact a B744 can takeoff without flaps is missing the point. Ground roll is not the only determining factor in determining whether or not a runway length is suitable. As private pilots know, the ability to clear objectives (a 50-foot obstacle) at the end of the runway is one additional factor. Most importantly, as multi-engine pilots know, is a thing called V1. This is the "takeoff safety" or "takeoff decision speed". It is a speed at which, with the failure of one engine, a multi-engine airplane may either 1) continue the takeoff and climb on the remaining engines or 2) stop the aircraft on the runway remaining.
So, unless you are taking off at Edwards AFB or on one of the other few, super long runways around the world, you won't be able to have a runway that meets V1 requirements with a no-flap takeoff in a B744. This is even more true with any sort of payload onboard. Secondly, you have to concern yourself with blowing out every tire on the aircraft.
Just because it "can" do something, doesn't mean that it is safe. The B707 demonstrated that it "can" do a complete roll at low altitude. That's certainly not something you want to do with passengers and really not recommended (or even legal) to be done at all... although, Tex Johnston's famous Seafair maneuver is legendary.
Proper use of checklists, good procedural "flows" and CRM practices hopefully eliminate most of the "forgetful" occurrences. Distractions can happen, ATC can and often does interrupt a flow or checklist call out, other things come up. That's why it's important to be extra vigilant during these instances. When all else falls, the "TAKEOFF CONFIG" warning comes in to save the day.
But as the B737 in Argentina shows... sometimes even the horns don't work... and they just go on blaring until the load "thud" at the end of the tape.
