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Biggles205

Rule of thumb approach speeds

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I'd be interested to hear more on the topic of calculating approach speeds.

Nil wind / gusting wind etc & also how this is effected by landing weight etc

 

Is there a simple rule to follow?

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If you throw the numbers into Aurasim, you'll get the correct results. Josh said to carry a bit of extra speed with you when fully established - 5-10 knots or so above Vref is a decent margin.

 

Stable approach criteria suggests not less than Vref but no more than 15 knots more however, although obviously in gusty conditions this is going to be more difficult. I'll put a note to get more clarification on this in the F.O training.  


website-splash-screen-smaller-.png| Ben Weston www.airline2sim.com 

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Thanks - Aurasim is neat tool. It was the approach speed above the Vref that I'm finding a bit hit or miss. If I'm not careful when I disconnect the A/P at 500ft the a/c just levels at about 300ft unless you give it some hefty nose down help

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Further to my post #3 the loss of GS at about 300ft has been corrected in the latest mjc Q400 patch 1.009

 

 

+ NavSources: Fixed the Glideslope disappearing during the operation on the runways equipped with 2 sided ILSs operating on the same frequency

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I think the "safety margin" between Vref and Vapp is half art and half science.  In the real world it is largely dictated by airline SOP.  The general pattern is Vapp = Vref + 5 kts + half steady state wind.  Occasionally, the gust factor is added in as well.  So as I see it, principally it is:

 

Vapp = Vref + 5kts (safety factor) + 0.5*Headwind (in case winds change). 


Eric Szczesniak

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It would have been worth me noting that there is usually an SOP maximum kts added to Vref.  This is because in high wind situations, the above formula (particularly if adding gust factor) can quickly add 20-30 kts and create very high landing speeds.  As I understand it, 15 kts is usually the maximum added ot Vref for the Dash 8.  Tube liners are usually more on the order of 20 kts.


Eric Szczesniak

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Hello,

 

From one of the largest Q400 operator:

 

 

2.12.8 Final Approach Speed
The final approach speed (VAPP) is the target speed for the final approach once the
landing configuration has been established.
Typical VREF values are 100 to 130 kts; so VREF provides a margin of between 20 to
30 kts above the stalling speed.
During a moderately turbulent approach, variations in IAS of up to 20 kts might occur.
A reduction in speed could bring the aircraft close to the stalling speed. In turbulent air,
it is acceptable to target a speed above VREF on the final approach in order to maintain
an adequate margin over the stall.
VAPP is calculated by applying a gust factor to VREF.
VAPP = VREF + gust factor.
 
 
The gust factor is half the variation in wind speed or 10 kts whichever is the lower. It
does not depend on the direction of the wind and is not bugged. For example, if the
wind is reported as 20 kts gusting 28, the gust factor is 4 kts.
 
Note: If VREF is already enhanced for any reason, then VAPP = VREF and the
approach is flown “on the bug”.
 
2.12.9 Threshold Speed
The threshold speed is the speed at which the aircraft should cross the threshold. The
basic threshold speed is VREF.
The aim is always to reduce the final approach speed such that the threshold is crossed
at VREF. If the threshold is crossed at speeds above VREF, the safety margins on
landing distance may not be met.
 
2.12.10 Touchdown Speed
The touchdown speed is the speed at which the aircraft touches down. If the threshold
is crossed at VREF and if the normal flare manoeuvre is performed, the touchdown
speed is normally 5 to 6 kts below VREF.
 
Hope this helps.
 
Regards
 
JP

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Will be sure to pay attention when the F.O version comes out. Bought your Cadet training and WOW, blown away. I have watched a lot of training videos and such before, but the people you got to help yours out are top notch. I was so relieved to see/hear the relaxed simple, yet informative way the videos had.


William Sequeira

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Will be sure to pay attention when the F.O version comes out. Bought your Cadet training and WOW, blown away. I have watched a lot of training videos and such before, but the people you got to help yours out are top notch. I was so relieved to see/hear the relaxed simple, yet informative way the videos had.

Thanks! FO training is about 12 weeks out :)


website-splash-screen-smaller-.png| Ben Weston www.airline2sim.com 

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Simple rule of thumb: 1.3 times the stall speed in landing configuration plus the wind speed plus 5 knots for the wife and kids.

Establish the landing configuration stall speed at altitude by lowering the landing gear and flaps. Reduce power, Pull back gradually, watch the noise go up, Keep an eye on the ASI and when you feel that pre stall buffet make a note of the speed on the ASI and that's your landing configuration stall speed:-)

 

Don't forget stick forward for stall recovery. LOL

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Simple rule of thumb: 1.3 times the stall speed in landing configuration plus the wind speed plus 5 knots for the wife and kids.

Establish the landing configuration stall speed at altitude by lowering the landing gear and flaps. Reduce power, Pull back gradually, watch the noise go up, Keep an eye on the ASI and when you feel that pre stall buffet make a note of the speed on the ASI and that's your landing configuration stall speed:-)

 

Don't forget stick forward for stall recovery. LOL

 

That's nuts.  It would be absolutely crazy for a pilot to establish their approach speed by first actually testing out the stall buffett! 

 

jpgmulti appears to have given the definitive answer to the question of V approach for the Q400.  

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No, I did not give the definitive answer. I only gave ONE answer by copying/pasting an Ops manual of an airline using Q400s. Other airlines would be slightly different but always basing the calculations on Vref.

 

Regarding Vref, when I was a young boy it was Vsx1.3 and now it is x1.23. Things change when performances change.

 

When you learn flying you are tought how to recover from a stall but you are not a test pilot and you do not establish yourself the stall speeds in different configurations to make all the calculations. In our case it has been done by Bombardier and you just follow the TOLD cards or AURASIM.

 

Personnally I do not think we should discuss this particular problem here as it has nothing do do with AIRLINE2SIM. We should do it on the MAJESTIC FORUM.

 

I take this opportunity to congratulate AIRLINE2SIM on their videos which are a great help when you want to fly the sim single handed as it is designed for two pilots.

 

Carry on the good work.

 

Regards.

 

JP

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