by tdammers » Tue Sep 01, 2020 12:25 pm
Landing speeds: with a large airliner like the 777, the landing reference speed (Vref) depends hugely on weight. Between operating empty and max landing weight, there is a 50% difference, and clearly a landing speed that works well for a 140-ton aircraft is going to have you drop out of the sky when you weigh 210 tons; and conversely, the right landing weight at 210 tons is going to make your float or nosewheel-strike when you're landing empty.
So what you need to do is find a resource for those landing speeds. Real-life pilots get a preliminary calculation from their dispatchers, who use dedicated software to calculate all the landing parameters; but it can also be done using tables from the FCOM, and in most modern airliners, the FMS can do the calculation as well.
The same goes for the takeoff. Here, the crucial speeds are V1, Vr, and V2. V1 is the "safe rejection speed": until V1 is reached, the aircraft can be brought to a full stop safely within the available remaining takeoff distance; once you're faster than V1, rejecting the takeoff may lead to an accident, and you are committed to the takeoff except for very severe problems (like losing both engines, loss of control, or a fire). Vr is the "rotation speed": this is the ideal speed to pull up the nose to initiate the liftoff. V2 is the "safe single-engine climb speed": after liftoff, your goal is to attain this speed ASAP, so that loss of one engine does not compromise the aircraft's ability to meet the minimum climb requirements for this takeoff.
In the FG 777, all these speeds are calculated automatically, and displayed on the PFD speed tape; Vref is shown as REF.
Then, procedures.
For the takeoff: Configure autobrake (RTO, "rejected takeoff"), flaps and trim, line up, arm A/T (the flip switches next to the speed selection on the glareshield panel), and rotate the speed selector to a suitable departure speed - at least V2, but typically something like 200-250 knots. This is to make sure that when the autothrottle kicks in, it keeps setting takeoff thrust at least until you have achieved V2. Set a suitable lateral mode on the autopilot: LNAV if you're flying an FMS flight plan, otherwise probably HDG. Revv up the engines to 40%, wait until they stabilize, then set takeoff thrust. At the "rotate" callout, pitch up; watch the vertical speed, as soon as it's consistently positive for 1 second, gear up. Maintain centerline and an attitude that keeps you speeding up to V2. Engage autopilot a couple hundred feet AGL, or later if you prefer hand-flying the aircraft a bit longer.
For the landing: Use the initial approach segment to slow down to your initial approach speed; typically, this would be your "minimum clean" speed (the slowest speed you can safely fly with no flaps deployed), something around 200-220 knots usually. The approach procedure will have you descend to a suitable ILS intercept altitude, typically about 2000-3000 ft AGL. Make sure you have the correct ILS frequency set, that the ground spoilers are armed, and that you have selected a suitable autobrake setting. As you turn onto your intercept heading, slow down to your initial approach speed (160-180 knots should work fine), and set flaps accordingly, and arm APP on the autopilot. Watch the aircraft intercept first the localizer, and then the glideslope. Once established on the glideslope, deploy landing gear. As you approach the outer marker (5 miles out), slow down to final approach speed (usually Vref + 10 knots), and deploy landing flaps.
Now you have the choice between autoland and landing manually.
For autoland, I believe all you have to do is watch the aircraft fly itself down to minimums, flare, align, retard, and touch down. Once on the ground, select reversers and set reverse thrust, verify that the ground spoilers and brakes are deploying, and use rudder to maintain centerline. At 60 knots, retard the throttles to reverse idle, and take over manual braking (the autobrakes should automatically disengage as soon as you touch the brakes). At 40 knots ground speed, disable thrust reversers; you may now take a high-speed exit while slowing down to taxi speed, or slow down further on the runway before taking a sharp exit. While vacating the runway, retract flaps, and switch off landing lights.
For a manual landing, the procedure is the same, except you disengage autopilot and autothrottle at some point during the approach - 1000 ft AGL is a good moment, but you can do it earlier if you want. Use pitch to control speed, throttle to control descent rate; keep airspeed at Vref + 10, and sink rate such that you stay on the ILS glideslope. Once you have a good visual of the runway, transition to a visual approach, using PAPI lights as your descent reference (two red, two white means you're on the glideslope). You should cross the runway threshold some 100-200 ft AGL, with some residual thrust on the engines (say 40-60% or so), a slight nose-up attitude, and a sink rate around 1000 fpm or so. At a suitable altitude (typically 50-100 ft AGL), retard the throttles; use pitch to arrest the descent - down to zero if you want a "butter" landing, or keep a little bit of sink rate if you want a safer, firmer landing. The aircraft should now just sink into the runway, main landing gear first. From here, the procedure is the same as above.