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Guest bruchpilot

Landing questions

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Guest bruchpilot

Hello,I have several landing questions:At what altitude to you turn off autothrottle?If A/T is off, how do you correct your descent rate, with rudder (pitch) or throttle?If I try a smooth landing I often hear the "glideslope" warning. Do I ignore it? Often ILS and PAPI/VASI lights don't match. What do I use as a reference?To the VREF30 speed of the FMC I add gusts and wind (max 20) and use that as approach speed, right? So when I flare at 50 or 30 ft I let the speed descent to VREF30 and let the plane hit the rwy with that speed?I hope to get good answers ;-)GreetingsEdgar

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I'll defer the landing procedure questions to those more experienced than I with the sim; however, often ILS and PAPI/VASI lights don't match in real world... but there is usually a statement as such on the approach plate. You didn't say which plane (737/747), but I've read that the cockpit height above nosewheel distance on the 747 is enough to warrant a different VASI setup. There are three-bar VASIs set up for the big heavies.


Dan Downs KCRP

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Hi Edgar,Have a look at the thread "Need help flaring please" which I think is on page 3 or 4 of this forum. This covers this topic quite well.Rudder does not control pitch...elevator does. Rudder yaws the nose of the aircraft left or right.There are two types of PAPI system. One for narrow body and one for wide. Most glideslope threshold crossing heights are 50ft. On a 747 the distance from the ILS G/S antenna to the undercarriage is 20 ft. The minimum wheel height crossing for a 747 is 22ft. If you add the two together you need 20+22=42 ft minimum G/S threshold crossing. With a PAPI you are not using the G/S antenna but the eyeballs and these are about 41ft above wheel height. So add 41+22 (min wheel height)=63ft. If a PAPI was set up for a 50ft crossing height you would need to make an allowance to the indications you see to make up for the extra 13ft needed for the 747 (63-50=13). A typical PAPI onslope indication would be 2 red lights and 2 white lights but for the 747 in order to make sure the threshold is crossed at the correct wheel height you need to fly the PAPI "one dot high". In other words you should see 3 white lights and one red. At some stage you will need to shift your attention from the ILS instrumentation to the PAPI. You should see the PAPI indicate the one red and 3 white lights. If you fly 2 white and 2 red then this will take you below the electronic G/S and you will get the aural alert "GLIDESLOPE".This is only general as different airfields have different published threshold crossing heights. This information can usually be found on the back of the ground chart (at least it is on Jepp charts). Hope this helps explain the difference.CheersSteve


Cheers

Steve Hall

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> At what altitude to you turn off autothrottle?At a minimum it should be off by 300 feet on finals.> If A/T is off, how do you correct your descent rate, with rudder(pitch) or throttle?A bit of both, but it HAS to be both, if you pull the nose back and don't add power, you will briefly alter the rate of descent, but within seconds will start to lose airspeed, and the aircraft will actually start sinking even faster.If you're too high on final, remove a small amount of power, lower the nose *slightly* and let the aircraft drift down onto the glideslope. Then bring the power back to where it was and raise the nose slightly.If you're too low, bring your power up, raise the nose *slightly* to stop the airspeed from increasing, and the aircraft will gradually come back onto the glideslope. Once you're back on the profile, reduce the power slightly, lower the nose a wee bit and you should hold the profile fomr there.The emphasis here is on making subtle changes. You should get established on the approach profile nice and early to allow this, if you are making big changes to your power or pitch below 1,500 feet you are probably going to have trouble, go around and try again.Oh and lastly, the pitch is actually controlled by the elevators, The rudder controls the yawing of the aircraft (left to right movement of the aircraft around a vertical axis.)Good luck with those approaches!


Mark Adeane - NZWN
Boeing777_Banner_BetaTeam.jpg

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"On a 747 the distance from the ILS G/S antenna to the undercarriage is 20 ft."The 744 is shorter than I thought it was :(Do you mean the G/S antenna are 20' higher than the main (wing/body) gear (lowest point of the tyres with bogies drooped) with the aircraft at a normal approach attitude?Thanks.Cheers.Q>

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Guest bruchpilot

>Rudder does not control pitch...elevator does. Rudder yaws the nose of >the aircraft left or right.... seems I was to tired to proofread...

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from my point of view, getting setup on the glideslope early is key. I am flying the approach manually from LOC capture, im learning to control the aircraft manually rather than relying on the autopilot. I have also started to fly departures manually by following the cues on the FD..great fun..its all about practise and knowing what your input on pitch and speed will have on the aircraft. Id recommend doing touch and gos at your favourite airport under different weather conditions to get a feel of the controls and how to get that glideslope under YOUR control and not go chasing that magenta diamond! Start under clear skies and no wind and progress from there when you feel your getting better.Good Luck!


Paul McMahon

Ireland

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Guest bruchpilot

Hi all,my question was more about the very last part of the final approach. Flare, high over threshold, VASI vs. ILS etc.GreetingsEdgar

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Sorry I should have made that more clear. Yes the vertical difference between the G/S antenna and the gear at normal approach attitudes.The G/S antenna transfers from the nose area to the nose gear door when the u/c is lowered. If 2 or more antenna do not transfer you will get an "ILS ANTENNA" EICAS caution message and you will need to add 8ft to the 20ft for the height of antenna above the u/c. Not that is likely to happen in the sim and I have never heard of it happening in the real world. CheersSteve


Cheers

Steve Hall

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