Altitude vs Distance

[Jim Padgett 11]

Is there a magic number for planning a flight where your altitude is lowered vs the distance your destination is?If I select IFR and Jet Airways do I have to have a destination that is far enough away from the departure location to get an altitude of say 14K ?If I use Copilot Pro to plan a flight that is 80-90 miles from departure I always get an altitude of 4000 ft even if I select Jet Airways.

[Guest jshyluk]

Airlines use a Flight Management Computer to calculate the optimal altitudes for waypoints. There are a number of variables, including the aircraft weight, atmospheric pressure, airspeed, availability of emergency airports, and so on that could go into figuring out that sort of information. Basically, though, you are looking for TOC (Top Of Climb) and TOD (Top Of Descent), which tells the autopilot when to stop climbing and when to start descending.Operationally, though, you will probably just follow the instructions given to you by ATC (Air Traffic Control). The ATC crew will follow your filed flight plan, which will use roughly the same calculations as your FMC. In your case, what I suspect is happening is that you are getting a TOD before you get a TOC, since the flight is very short. You won't be getting to the jet airways (FSX call them, what? High Level airways), so your flight plan gets confined to the low level airways, which won't go above 10,000.Add to that, many SIDS and STARS (departures and approaches) typically have their entry and exit altitudes at say between 3,000 tp 5,000 feet AGL (above ground level). With a flight that goes less than one hundred miles, you might be leaving a SID at 4,000 and jumping into a STAR again at 4,000. If you can find approach and departure plates for the airports you are using, this will answer that question. Many plates can be found for free on the Internet. So, the short answer, is yes, you do need locations that are sufficiently far apart to have room for a TOC that will allow you to reach a jet airway. How far that distance is will depend on how you climb your aircraft. I hope I have answered your question; it's a little more technical than I am used to, so if I've made a mistake, or if there is more, maybe someone else will chime in.Jeff ShylukAssistant Managing EditorSenior Staff ReviewerAVSIM

[Guest RonB49]

Years ago I lived in Springfield Illinois. Ozark Airlines flew some DC9s between Springfield and St Louis (about 75 air miles as I recall). They would climb and climb and climb, then drop right out of the sky at the other end. I remember them flying between FL200 and perhaps FL230 in that short distance. The better ride (although quite noisy) were their F27s. With the high wing, big windows, and lower altitude they were great for sightseeing; not that there are many sights to see on the Illinois prairie.R-

[Bert Pieke 7,585]

Here is some simple math:Assume you climb and descend at 1000ft/minTo get up to 14k and down again would take about half an hour.14 + 14 = 28..Half an hour at 240 knots is about 150 miles..And that does not give you any time to cruise at 14,000 ft BTW.. :-)

[Bunchy 227]

I've always used the distance of the flight as a flight level.eg. 140nm flight at FL140 (adjusted up or down a thousand feet for flight level direction rules)Any flight over 300nm, you can fly at the max the aircraft is capable of (weight and ATC permitting)Stu.

[Guest RonB49]

I must ask Bert and Stu what we are flying here. Assuming a passenger jet, then I think both of these equasions are wrong. Southwest used to allow 55 minutes gate-to-gate for a 737 between San Antonio KSAT and Dallas Love KDAL that is about 220 Nm. I say, "used to," because I don't fly much anymore but I think that they have extended those times recently. But the exact time makes little difference, the in-air time is still less than an hour. They always fly above FL300. Plus, their flight attendants had time get me a beer to go with my peanuts.R-EDIT -- kaws i cant type. R-

[Guest fsxmissionguy]

"Plus, their flight attendants had time get me a beer to go with my peanuts."OK. Now you're really dating yourself. Since when can you get a beer on a flight?Or peanuts?Or a flight attendant?

[Geofa 108]

Are we speaking of the passenger or the pilot? }(http://www.mediafire.com/imgbnc.php/1b5baf...b9f427f694g.jpgMy blog:http://geofageofa.spaces.live.com/

[Guest RonB49]

>Are we speaking of the passenger or the pilot? }(Only the former - - - I hope. ;)R-

[Guest bstolle]

FMC or not (the wind in the descent forecast page might not be up to date etc...)In a 767 or a C152 I always use the very basic formula: distance x 3 = altitudeE.g. You need to start the descent when 100NM from the airport at 30000ft.(Because this is so easy) I recalculate every 10NM to apply necessary corrections to flatten or steepen the descent a bit.RegardsBernt Capt 767