General Route Pre-Planning Questions

[Bman2006 7]

Afternoon all-

 

I have had been reading up and getting attuned to a more efficient pre-planning and have come up with a couple of questions. Keep in mind, this is all pre-planning, prior to getting into the cockpit.

 

1) What is the best way to determine the optimal cruise altitude without the FMC telling you. I suppose it's largely based around the cost index (assuming you have kept clear of obvious MEA etc). Is there any way to know in advance so this information can be input into FSBuild (or any other planning tool) of where you plan on being at cruise?

 

2) Preselecting SID / STARs - if you are going be flying online .. have you been simply not including these in the preplanning or do you take your best guess during planning and then just change the route in the FMC once you have clearance & delivery?

 

3) Flap configuration - I would have sworn that I read that 5 is the base standard setting. Adjust according to available runway length if needed?

 

4) Looking at TopCat, I see that if I select a higher assumed temperature derate, the v-speeds change. Why is this? My guess guess is that as you reduce the N1, you have to build in additional speed for buffer in the event you have sort of issue during liftoff / rollout and the engines are derated and would take longer to adjust for any loss of thrust? This is just a guess as the actual liftoff speed would be physically the same V1/V2/Vr based on weight of plane at takeoff. So, I guess the question is why the increased v-speeds with higher derate / lower N1?

 

Thanks-

 

Benjamin

[sandpatch 9]

3) I go by TOPCAT's recommended setting but I I think that the standard selection is 1. Might be a different SOPs for different airlines.

[PHXMD-11 86]

What is the best way to determine the optimal cruise altitude without the FMC telling you.

 

I think this would become more apparent as you learn to fly the aircraft. Higher weights mean a lower altitude. Lower weights and you'll be able to initially cruise at higher levels.

 

Preselecting SID / STARs - if you are going be flying online .. have you been simply not including these in the preplanning or do you take your best guess during planning and then just change the route in the FMC once you have clearance & delivery?

 

Look at the active runways. This will cut the number of SIDs/STARs down a bit. Then look at those that go along with your planned route. If you're taking off from LAX off 24/25 and the enroute waypoint is DAG, then you can choose the LOOP and LAX (if I remember those correctly).

 

Looking at TopCat, I see that if I select a higher assumed temperature derate, the v-speeds change.

 

The speeds will increase a bit if a higher derating is chosen.

 

Flap configuration - I would have sworn that I read that 5 is the base standard setting. Adjust according to available runway length if needed?

 

Depends on airline SOP. Some use 1. Some use 5. Some use whatever is said on the pilot's paperwork.

[Bman2006 7]

Thanks for the response-

 

Right, that's generally plan my SID/STARs but on the occiasion they do change if a different runway becomes active prior to departure (vatsim). It's rare though.

 

View PostBman2006, on 22 June 2012 - 02:18 PM, said:

Looking at TopCat, I see that if I select a higher assumed temperature derate, the v-speeds change.

 

The speeds will increase a bit if a higher derating is chosen.

 

Right - I see that, the question is why do the speeds increase. What the function of the increased speeds?

 

Benjamin

[MED1473 18]

Hi all!

Just wondering what you mean about v speeds increasing?

Surely if you lower engine performance by derating v1 decreases?

Matteo capocefalo, Med14732

[Bman2006 7]

Matteo - Never mind - I think I have lost my mind. I can't seems to replicate what I was seeing earlier with the derate increasing and vspeed also increasing. I think what I was actually looking at was different runways with different wind conditions TW versus HW changing the Vspeeds. That would make a lot more sense.

 

 

So back to the whole SID / STAR pre-planning bit, what are you doing to analyze the charts ahead of time? For example, I am planning a flight from LOWI - Innsbruck to ~ where can I to go review the charts to see which way they are heading? I suppose I track down the charts online some where and then plug in the SID prior to building the flight plan. Or, I can select a departure, build, select another departure, build. I am 100% unfamiliar with the airport so I guess looking online for charts first is a must prior to building the plan?

 

Benjamin

[PHXMD-11 86]

I think I have lost my mind

 

I'm not an expert so disregard my saying that the V-speeds increase.

 

where can I to go review the charts to see which way they are heading

 

For airports in the US, Flight Aware has charts on its website. For airports in Europe, go to www.ead.eurocontrol.int. You have to register but it is free. The charts are updated but may be out of date.

[Bman2006 7]

Yeah, I like flightaware, skyvector and flyplan

 

So, really there is no way around going and looking at each of the SIDs prior to building the plan otherwise one would simply be guessing. I didn't know if there was a "viewer" of sorts in FSBuild.

[dmbusmc 46]

Hey Benjamin. There are several ways to get charts online. The most simple and quickest way would be just Google them. For instance, I just typed "LOWI charts" in Google, and this .pdf set was the first that came up: http://va-transaero.ru/files/charts/LOWI.pdf

 

In addition to the sites above, for the U.S. use AirNav, here: http://www.airnav.com/airports/

 

And for the UK here: http://www.nats-uk.ead-it.com/public/index.php.html

 

Anywhere else in the world Google has very very very rarely failed me, just type in the ICAO identifier and "charts" and look for the .pdf's! As said before though while they may get updated they might not be 100% current, but I have seldom come across any problems caused by this, in fact off the top of my head I can't think of any instance that this happened.

 

Happy flying,

 

Kyle

[MED1473 18]

Hi Ben,

Just realized I was very wrong, V1 shouldn't decrease with derate. Not sure about this but the way I see it V speeds are not a variable of engine derates, especially concerning OAT derate. V2 is to some extent dependent on a fixed derate. V1 and Vr should stay the same independently on the derate you choose that becomes a factor only on takeoff run. (less power available=longer distance to reach the speed).

Sorry about the confusion but I'm pretty sure if you have a look through the CTM in the ngx docs engine derating is discussed.

Hope it helps, Matteo MED1473

[maddoc 0]

4) if you select an higher flex temp derate you obtain lower N1; so you have lower engine trust power and then higher speed to liftoff

 

If you select lower flex temp you'll have an higher N1 and then more engine power so you need a bit lower speed to liftoff

[wisefox7524 9]

Usually, if you can, the higher cruise altitude, the better. I usually fly real-world routes, so I can find them on flight aware, which gives you all the essential information. If for some reason I'm not flying a real-world route, I break out the SIDS/STARS and enroute charts, and manually plot the course. If I'm doing that, I'll usually use a CI of 50, and if I'm flying above FL350, I usually use a TAS of 450...remember for cruising altitudes, if your heading east, pick and odd altitude, and west, and even altitude.

Also, Flaps 5 is the standard 737 take-off setting. Flaps 1 is usually used at high/hot airports.

 

I really can't wait for PFPX. I've said this before, but it should take care of all of our flight planning problems.

[maddoc 0]

About the cruise flight level the fmc reports the operational optimum flight level and the maximum flight level you can fly considering your weight and the fuel on board; I suggest you to use that flight level, you'll find it in the CRZ speed page and in PERF page of NGX FMC

 

 

[rsvit 16]

About the cruise flight level the fmc reports the operational optimum flight level and the maximum flight level you can fly considering your weight and the fuel on board; I suggest you to use that flight level, you'll find it in the CRZ speed page and in PERF page of NGX FMC

 

For flights less than 300-350nm altitude on PERF INIT page takes into consideration distance, winds, field elevations, ISA DEV. So if you are flying short haul take optimum altitude from there.