landing speed question

[Guest presario]

Is the proper landing speed Vref or Vref plus 1/2 the headwind speeds?I ask because approaching the runway fully configured and at Vref speeds tends to make the plane pitch up pretty high making it hard to see the approach.Presario

[Guest presario]

No one has any idea about this? Seems like a pretty important topic to me.. the FMC has a line under the Vref approach speed thats stuck on wind correction +5kts, I'm sure this in an inop button but it also raises the question of what's the proper approach speed, Vref or Vref plus 1/2 the headwind speed.. e.g. Vref 30 = 131kts Headwinds speed 12kts makes the proper approach speed 137kts.. is this right? anyone?

[Guest merlin2]

Hope this helps. On final approach, the airplane will react to windshear and gusts for both the headwind andcrosswind components of the wind. Unless compensated for, these factors may cause the airplaneto land short.

[Guest presario]

This is good information Howard thanks. I'm still confused about the proper MCP speed needed for a full autoland approach. In your message you say "With the autothrottles disengaged, use an approach speed wind correction of 1/2 the steady headwind component" does this mean that when autothrottle is engaged that Vref only should be placed in the MCP? Isn't autothrottle most usefull when landing?Presario

[Guest merlin2]

doing a full auto land (rare)when setting your flaps for landing v-ref +5 in M.C.P with no wind corrections and leave on auto throtlles. on a manual landing add the wind speeds.Howard

[Guest Pittsburgh]

Hi, Very interesting indeed, Howard :) Now that you seem to know a lot about the subject, I will shoot a question: When setting up the speeds, and as you decelerate, at some point, there is a white bug on the speed tape. Now, I don't have the manuals here (am off on vacation), so I can look to see what it is for. Do you by any chance know that?Thanks :-waveBoaz

[crvm 0]

VREF + 15 BUG, I assume it's the same on landing........[h4]Best Wishes,Randy J. Smithhttp://www.precisionmanuals.com/images/betaimg.jpg

[Guest merlin2]

what he is seeing is "Bug 5", the white speed-ref bug that can be set up on the cockpit displays. It can be set with a little knob above your engine displays. Its called SPD REF Normally its on auto so all your speed bugs come from the FMC. However, you can manually set V1, VR, Gross Weight, VREF on the ground to override the FMC if you need too with bug5 (the 5th one you can set obviously) being just a pilot selectable speed for any reason he might need it. You can go out of auto mode and select bug5 to get all your automatic readings plus the airspeed you select too. Its sometimes handy for showing an ATC speed restriction on your speed tape.. hope this helps :)Howard

[Guest rcarlson123]

Reading this thread triggers a question I've had for a while now. What is the correct way to add flaps on approach to landing? I never know when exactly I should be at each flap setting.Let's say I have selected a 30 degree flaps approach. When should I be at 5, 10, 15, 25, and 30 degrees? And how should the plane be slowed down? Normally I stay at the last ATC speed (usually 250 knots) until I'm on an intercept course for the localizer. Then I slow to 180 knots and set 5 degrees flaps. When I'm established, I set 10 degrees and slow to 160. Then between 5 and 10 miles on final, I set the final approach speed and go to 30 degrees flaps.Should I instead by setting final approach speed as soon as I'm established, then add flaps according to the flap speeds placard as the plane decelerates?I'd love some input on the proper and realistic way to slow the plane and add flaps on approach.Thanks!

[Guest Iz]

Here are some rules of thumb for an ILS:5 miles to G/S intercept: flaps 5 / speed 5 (on the 5 bug)1500 ft RA: gear down, flaps 15 / speed 151000 ft RA: flaps 30 / final approach speedThis is a low noise/low drag approach. A standard ILS or a non-precision approach would be:5-8 miles to final descent point: flaps 5 / speed 52 miles to descent point: gear down, flaps 15 / speed 151 mile to descent point: flaps 30, then 40 / final approach speedIz

[Guest merlin2]

From your INI REFS PAGE SELECT YOUR FINAL FLAPS SPEEDS. when maneuvering to intercept the localizer, decelerate and extend flaps to 5. Attempt to be at flaps 5 and flaps 5 maneuvering speed prior to localizer capture.When glideslope alive select flaps 15 gear down and arm speed brake.At glideslope capture observe the annunciation change. At this time, select landing flaps and VREF plus 5 knots or VREF + wind correction if landing manually, and complete the landing checklist.When using the autothrottles to touchdown, no additional wind correction to the final approach no speed is required. MAX FLAP SPEEDS. VMO / MMO

[Guest rcarlson123]

Thank you, Howard and Iz, for this information!

[Guest ba747heavy]

I wrote this 'equation' wrong in my tutorial, so my apologies.....The correect landing speed is VRef + (1/2 * wind component) + (gust componoent)So with the following conditions - wind 4 gust to 9, VRef of 135, you do:135 + (1/2 * 4) + 9 = 136 knots :)

[Guest Iz]

Hmm well, to me, 135 + 2 + 9 is still 146 :)But the gust component in this example is not 9, it's 5 (9 minus 4 knots steady wind). So you would end up with 135 + 2 + 5 = 142 knots for FAS.