How do you determine what cruise altitude to use when flight planning.

Only thing I can think of off the top of my head is the direction you're flying, weather, weight, and where you're flying. Probably more that I don't know off hand.

That would greatly depend on the type of aircraft along wit a few other factors. You wouldn't use 36000 ft for a cessna 172 or 5000 ft for a 737.

For IFR:

 

§ 91.179   IFR cruising altitude or flight level.

(a) In controlled airspace. Each person operating an aircraft under IFR in level cruising flight in controlled airspace shall maintain the altitude or flight level assigned that aircraft by ATC. However, if the ATC clearance assigns “VFR conditions on-top,” that person shall maintain an altitude or flight level as prescribed by §91.159.

( B) In uncontrolled airspace. Except while in a holding pattern of 2 minutes or less or while turning, each person operating an aircraft under IFR in level cruising flight in uncontrolled airspace shall maintain an appropriate altitude as follows:

(1) When operating below 18,000 feet MSL and—

(i) On a magnetic course of zero degrees through 179 degrees, any odd thousand foot MSL altitude (such as 3,000, 5,000, or 7,000); or

(ii) On a magnetic course of 180 degrees through 359 degrees, any even thousand foot MSL altitude (such as 2,000, 4,000, or 6,000).

(2) When operating at or above 18,000 feet MSL but below flight level 290, and—

(i) On a magnetic course of zero degrees through 179 degrees, any odd flight level (such as 190, 210, or 230); or

(ii) On a magnetic course of 180 degrees through 359 degrees, any even flight level (such as 180, 200, or 220).

(3) When operating at flight level 290 and above in non-RVSM airspace, and—

(i) On a magnetic course of zero degrees through 179 degrees, any flight level, at 4,000-foot intervals, beginning at and including flight level 290 (such as flight level 290, 330, or 370); or

(ii) On a magnetic course of 180 degrees through 359 degrees, any flight level, at 4,000-foot intervals, beginning at and including flight level 310 (such as flight level 310, 350, or 390).

(4) When operating at flight level 290 and above in airspace designated as Reduced Vertical Separation Minimum (RVSM) airspace and—

(i) On a magnetic course of zero degrees through 179 degrees, any odd flight level, at 2,000-foot intervals beginning at and including flight level 290 (such as flight level 290, 310, 330, 350, 370, 390, 410); or

(ii) On a magnetic course of 180 degrees through 359 degrees, any even flight level, at 2000-foot intervals beginning at and including flight level 300 (such as 300, 320, 340, 360, 380, 400).

 

For VFR:

 

§ 91.159   VFR cruising altitude or flight level.

Except while holding in a holding pattern of 2 minutes or less, or while turning, each person operating an aircraft under VFR in level cruising flight more than 3,000 feet above the surface shall maintain the appropriate altitude or flight level prescribed below, unless otherwise authorized by ATC:

(a) When operating below 18,000 feet MSL and—

(1) On a magnetic course of zero degrees through 179 degrees, any odd thousand foot MSL altitude +500 feet (such as 3,500, 5,500, or 7,500); or

(2) On a magnetic course of 180 degrees through 359 degrees, any even thousand foot MSL altitude +500 feet (such as 4,500, 6,500, or 8,500).

( B) When operating above 18,000 feet MSL, maintain the altitude or flight level assigned by ATC.

 

** Copied from the VATSIM ZLA site. **

http://forum.avsim.net/topic/384544-how-high-do-i-fly/

 

I like the rule of multiplying distance by 100, eg 250nm trip = FL250 cruise. Remember odd thousands for east headings, even thousands for west.

I use whatever the real flight used on flight aware. 

How do you determine what cruise altitude to use when flight planning.

I plan it like ATC would do it. It all depends on the Jetstream flow of the day (airliner flying only). Going west I'm at and even altitude (32,000ft), going east I'm at an odd altitude (37,000ft). Your always fighting high winds going from east to west so I don't bother getting to the higher 30's as it's not helping much anyway. When your fighting a 100kt headwind it only get's worse at 40,000ft versus 32,000ft (in the real world other factors are going on if an airliner is required to fly higher in a strong headwind, usually traffic separation issues).

 

Going east I always fly high to take advantage of the high winds heading east. As was mentioned already 'FlightAware' is a good reference if you simulating a specific flight but the jetstream is a huge factor in what altitude you choose to get the best bang for you buck (the difference of going 360kts ground speed versus 596kts over the ground).

I plan it like ATC would do it. It all depends on the Jetstream flow of the day (airliner flying only). Going west I'm at and even altitude (32,000ft), going east I'm at an odd altitude (37,000ft). Your always fighting high winds going from east to west so I don't bother getting to the higher 30's as it's not helping much anyway. When your fighting a 100kt headwind it only get's worse at 40,000ft versus 32,000ft (in the real world other factors are going on if an airliner is required to fly higher in a strong headwind, usually traffic separation issues).

 

Going east I always fly high to take advantage of the high winds heading east. As was mentioned already 'FlightAware' is a good reference if you simulating a specific flight but the jetstream is a huge factor in what altitude you choose to get the best bang for you buck (the difference of going 360kts ground speed versus 596kts over the ground).

The best way would be to check winds aloft. We flew with tailwinds both to the east and to the west by flying the pressure systems. We flew north around a high pressure and the next day we made a southerly route going back home and had tailwinds both times.

 

Higher altitudes don't always mean higher wind speeds. We usually go higher going west as well because our fuel burn is so much better. We will get to our destination 10 minutes latter but we saved hundreds of pounds of fuel.

The best way would be to check winds aloft. We flew with tailwinds both to the east and to the west by flying the pressure systems. We flew north around a high pressure and the next day we made a southerly route going back home and had tailwinds both times.

 

Higher altitudes don't always mean higher wind speeds. We usually go higher going west as well because our fuel burn is so much better. We will get to our destination 10 minutes latter but we saved hundreds of pounds of fuel.

 

Thanks. As I said above it depends on the jetstream as to what one is getting from day to day and airline routing takes these things into consideration. As far as the fuel burn I guess we learn something new everyday... To get a better fuel burn while fighting a head wind of 60+kts is new information to me. What airline do you fly for?

Access to good upper wind data is difficult in a flight simming context. It would be great if we had dispatcher-type software which accesses this data.  However, the number of free and easily-available sources of this data is not plentiful.

Access to good upper wind data is difficult in a flight simming context. It would be great if we had dispatcher-type software which accesses this data.  However, the number of free and easily-available sources of this data is not plentiful.

This site has worked for me in conjunction with Activesky Evolution...

 

http://www.intellicast.com/National/Wind/JetStream.aspx

Thanks. As I said above it depends on the jetstream as to what one is getting from day to day and airline routing takes these things into consideration. As far as the fuel burn I guess we learn something new everyday... To get a better fuel burn while fighting a head wind of 60+kts is new information to me. What airline do you fly for?

I don't fly for an airline anymore but that didn't matter since we were flying Dash-8s and ATR-72s below 10,000'. I fly a King Air from the west coast to the east coast.

 

The difference for us between FL290 and FL350 can be 2 hours of fuel depending on temperatures. The best free reading on th subject is in the Aerodyamics for Naval Aviators found for free on FAA.gov. Check page 168 of the book and read to 176. It talks about reciprocal engines, turboprops and turbojet efficiencies.

I don't fly for an airline anymore but that didn't matter since we were flying Dash-8s and ATR-72s below 10,000'. I fly a King Air from the west coast to the east coast.

 

The difference for us between FL290 and FL350 can be 2 hours of fuel depending on temperatures. The best free reading on th subject is in the Aerodyamics for Naval Aviators found for free on FAA.gov. Check page 168 of the book and read to 176. It talks about reciprocal engines, turboprops and turbojet efficiencies.

 

Got it, I was more so talking about jet airliners.

Got it, I was more so talking about jet airliners.

I'm pretty sure I was talking jets as well. Unless jet airliners are able to defy physics.

Got it, I was more so talking about jet airliners.

I'm pretty sure I was talking jets as well. Unless jet airliners are able to defy physics.

You can find here optimum flight level for DC9, MD80/90 and B767 http://www.hilmerby.com/fom/proc_fl.html 

 

I use this with Leonardo Maddog. With PMDG NGX and MD11, FMC will give you optimum / maximum FL