dnunes

Landing Data

Recommended Posts

I have now progressed in flying the 777. I think I am missing something: with the TOPER Calculator I am able to introduce weather data to calculate the take off conditions. But what about the landing? I do not see how to introduce weather data to calculate the landing approach speed (VREF). What am I missing?

Regards,

Domingos

Share this post


Link to post
Share on other sites
Help AVSIM continue to serve you!
Please donate today!

6 minutes ago, dnunes said:

What am I missing?

That would be a question for the people who made TOPER.

Share this post


Link to post
Share on other sites

VREF is based on weight of the aircraft and not on weather. It is usually 1.3 times the stall speed for the configuration. Weather does not play into when an aircraft will stall, so there is no need. The ref speeds the FMS will provide are the correct ones.

  • Upvote 1

Share this post


Link to post
Share on other sites

Thanks Kyle for your reply. TOPER provides data for takeoff, not landing. For the Airbus I have a similar tool to calculate the takeoff data, For the landing I introduce in the FMC the weather data (QNH, wind, temp) to calculate Vref. Maybe that for the bigger 777 weather data is not relevant.

Regards,

Domingos

Share this post


Link to post
Share on other sites

Thanks Nick for your reply. My previous reply to Kyle is in line with your information. It is a long time since I stopped flying the iFly737 but I think it also required weather input for then landing.

Regards,

Domingos

Share this post


Link to post
Share on other sites
5 minutes ago, dnunes said:

Thanks Kyle for your reply. TOPER provides data for takeoff, not landing. For the Airbus I have a similar tool to calculate the takeoff data, For the landing I introduce in the FMC the weather data (QNH, wind, temp) to calculate Vref. Maybe that for the bigger 777 weather data is not relevant.

Vref should always be the same, to my knowledge, but if the software is calculating rollout, and other distance-based info, that would be affected by wind at the very least.

Share this post


Link to post
Share on other sites

Thanks Kyle for your reply. l would expect that, as it happens with the Airbus, Vref would depend on the weight of the aircraft at landing, as well on with weather conditions: wind speed and direction, temperature... Isn't this always the case with any aircraft?

Regards,

Domingos Nunes

Share this post


Link to post
Share on other sites
5 hours ago, scandinavian13 said:

Vref should always be the same, to my knowledge, but if the software is calculating rollout, and other distance-based info, that would be affected by wind at the very least.

altitude is changing a little VREF but by 1 or 2 knots at max ...

Share this post


Link to post
Share on other sites
Posted (edited)
55 minutes ago, dnunes said:

Thanks Kyle for your reply. l would expect that, as it happens with the Airbus, Vref would depend on the weight of the aircraft at landing, as well on with weather conditions: wind speed and direction, temperature... Isn't this always the case with any aircraft?

Regards,

Domingos Nunes

On the 777, Vref is only weight dependent.

Actually it is the same as Airbus Vref = Vls on the landing distance calculation guide in the QRH, but on the airbus the amount of headwind component of greater than 15kts will change a the approach correction which increases the to above 5 kts. And as you have already know the standard airbus Vapp is Vls + approach correction which is quite often Vls + 5 just like the 777.

 

on the 777, life is much easier. Wind never changes the Vapp which is always Vref 30 or 25 or 20 (for eng out) + 5 kts, unless the wx condition is necessary for the pilots to bug up more up to Vref + 20kts. But the books says the A/T is react fast enough in gusty condition even without any bug up.

 

in general, on the 777 wind only affects the landing distance but not the Approach speed. 

 

Elevation of an airport may be significantly affects the landing distance. Low QNH has similar effect as landing at an airport with some elevation but never have a significant effect. Temperature is usually not a big factor. 

 

 

 

 

Edited by Driverab330
  • Upvote 1

Share this post


Link to post
Share on other sites
1 hour ago, Driverab330 said:

on the 777, life is much easier.

The AOA never lies.  Although I set my approach speeds in the FMC, I fly the approach using the AOA.  

I started using the AOA when flying in the military, and it carried over into my civilian and commercial career. 

Share this post


Link to post
Share on other sites
2 hours ago, Driverab330 said:

On the 777, Vref is only weight dependent.

Actually it is the same as Airbus Vref = Vls on the landing distance calculation guide in the QRH, but on the airbus the amount of headwind component of greater than 15kts will change a the approach correction which increases the to above 5 kts. And as you have already know the standard airbus Vapp is Vls + approach correction which is quite often Vls + 5 just like the 777.

 

on the 777, life is much easier. Wind never changes the Vapp which is always Vref 30 or 25 or 20 (for eng out) + 5 kts, unless the wx condition is necessary for the pilots to bug up more up to Vref + 20kts. But the books says the A/T is react fast enough in gusty condition even without any bug up.

 

in general, on the 777 wind only affects the landing distance but not the Approach speed. 

 

Elevation of an airport may be significantly affects the landing distance. Low QNH has similar effect as landing at an airport with some elevation but never have a significant effect. Temperature is usually not a big factor. 

 

 

 

 

VREF for the LR is affected by pressure altitude.

 

at 240t the vref30 is 143 knots at sea level at 4000` it will be 144 knots. taken from QRH ...

Share this post


Link to post
Share on other sites
1 hour ago, phil747fan said:

VREF for the LR is affected by pressure altitude.

 

at 240t the vref30 is 143 knots at sea level at 4000` it will be 144 knots. taken from QRH ...

Thx for the info, I have never have the privilege to fly the 772LR in real life which I would love to.

 

Share this post


Link to post
Share on other sites
1 hour ago, phil747fan said:

VREF for the LR is affected by pressure altitude.

 

at 240t the vref30 is 143 knots at sea level at 4000` it will be 144 knots. taken from QRH ...

Do you think that is more accurate than the data presented by the AOA?

Share this post


Link to post
Share on other sites
4 hours ago, Bluestar said:

Do you think that is more accurate than the data presented by the AOA?

Here is my take on it. Flying by AOA is a good thing, however, in the situation of the 200LR, AOA would not matter. The 200LR has varying REF speeds to handle VMCA in the event of an engine failure during the GA phase of flight. Boeing wants you to have the extra speed to give you a larger safety margin because of this. AOA would not matter in this case as AOA will not tell you when you have VMCA'd the aircraft. 

6 hours ago, phil747fan said:

VREF for the LR is affected by pressure altitude.

 

at 240t the vref30 is 143 knots at sea level at 4000` it will be 144 knots. taken from QRH ...

You are correct. It is one of the rare aircraft where that is the case. Due to the shorter fuselage of the 200LR compared to the 300ER, the additional speed is needed for control ability reasons. A higher PA will result in less air moving over the wings at a given time, requiring a higher speed to be able to handle the asymmetric thrust in the event of an engine failure during a GA situation.

  • Like 1

Share this post


Link to post
Share on other sites
10 hours ago, Bluestar said:

The AOA never lies.  Although I set my approach speeds in the FMC, I fly the approach using the AOA.  

I started using the AOA when flying in the military, and it carried over into my civilian and commercial career. 

Exactly. I've found a lot of the military guys I've flown with fly the AoA more than the speed. Is an AoA gauge pretty common equipage in that area? I know a lot of the fighters have an AoA gauge (or an over/under/on indicator, really) by the HUD somewhere, but is that something that they teach/practice pretty consistently across the board?

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now