Guide
Altitude and flight levels: who flies how high
Most airliners cruise between 33,000 and 41,000 ft, business jets go higher (up to 51,000 ft), regional jets typically fly between 25,000 and 37,000 ft, and most light aircraft stay below 10,000 ft. Above 18,000 ft in the US, altitude is expressed in flight levels, so 35,000 ft is "FL350."
Transition altitude and flight levels
Aircraft altimeters measure air pressure. Near the ground, pilots set the local pressure so the altimeter shows height above sea level accurately enough to clear terrain and land. At high altitude, what matters is that every aircraft uses the same reference so they stay separated. In the US, the switch happens at the transition altitude of 18,000 ft. Above it, every pilot sets the standard pressure of 29.92 inHg (1013.25 hPa) and altitudes are read as flight levels: FL180, FL250, FL350 and so on, each the pressure altitude in hundreds of feet.
Airspace from 18,000 ft MSL up to FL600 is Class A: all aircraft must fly under instrument flight rules (IFR) with an ATC clearance and, since 2020, carry 1090 MHz ADS-B Out. In many other countries the transition altitude is much lower and varies by airport, for example 6,000 ft at many UK airports.
Cruising altitudes
For IFR flights in the US, direction of flight decides odd or even levels: aircraft tracking roughly east (0° to 179°) fly at odd thousands (FL330, FL350, FL370), and those tracking west (180° to 359°) at even thousands (FL340, FL360, FL380). VFR pilots above 3,000 ft above ground add 500 ft (for example 5,500 or 6,500 ft).
Who flies at which altitude
| Band | Typical traffic |
|---|---|
| Ground | Aircraft taxiing or parked with transponders on |
| 0 to 10,000 ft | Light aircraft, helicopters, flight training, and airliners departing or arriving |
| 10,000 to 20,000 ft | Turboprops, piston twins, airliners climbing or descending |
| 20,000 to 30,000 ft | Regional turboprops and jets, short flights, aircraft stepping up to cruise |
| 30,000 to 40,000 ft | Most airliners and many business jets in cruise |
| 40,000 ft and above | Business jets and some long-haul widebodies late in their flights |
These are the bands used in the altitude chart on our live dashboard. The 10,000 ft line matters because in the US the 250-knot speed limit applies below it. The 18,000 ft line is the start of Class A airspace, and 40,000 ft is where airliners mostly top out, leaving the band above to business jets.
Light aircraft
A Cessna 172 typically cruises at 3,000 to 10,000 ft. Unpressurized aircraft rarely go above 12,500 ft because FAA rules require crew oxygen above that for extended periods.
Regional and narrowbody jets
Regional jets like the Embraer 175 and CRJ900 often cruise in the FL300s on longer legs but lower on short hops. Narrowbodies like the 737-800 and A320 usually cruise at FL330 to FL390.
Widebodies
Long-haul jets often start lower because they are heavy with fuel, then "step climb" as they burn it off, reaching FL390 to FL430 on aircraft like the 787-9 and A350-900.
Business jets
Business jets are certified for higher ceilings, which gets them above airline traffic and weather: up to 51,000 ft for the Gulfstream G650 and 45,000 ft for many midsize jets. These usually dominate our highest right now list.
Higher still
Concorde cruised at around 55,000 to 60,000 ft. High-altitude research and reconnaissance aircraft such as the U-2 fly above 70,000 ft, but rarely broadcast. Stratospheric research balloons can float at 100,000 ft or more and occasionally appear on trackers with emitter category B2 (lighter-than-air). See helicopters, balloons and oddities.
Why altitude changes so much on a short flight
Not every airliner reaches the FL300s. On a 150-mile hop such as Los Angeles to Las Vegas, a jet may climb to the low FL200s and start down almost immediately, because the fuel saved by climbing higher would not pay back the time spent getting there. Controllers also cap altitudes to keep arrival and departure streams apart near busy hubs, so a flight out of New York may hold at 10,000 or 17,000 ft for some time before being released higher. That is why, at any moment, the 10,000 to 30,000 ft bands on our chart hold a substantial share of the jets in the sky, not just the turboprops.
Barometric vs GPS altitude
Trackers show barometric altitude because that is what ATC uses. GPS (geometric) altitude can differ by several hundred feet, especially on very hot or very cold days. The difference is normal. More in how to read flight data.
Questions
How high do commercial planes fly?
Most airliners cruise between 33,000 and 41,000 ft. Long-haul jets often start lower and step-climb as they burn fuel; regional jets often cruise lower on short flights.
What is a flight level?
A flight level is altitude based on standard pressure, given in hundreds of feet. In the US it applies at and above 18,000 ft, so FL350 means 35,000 ft on a standard-pressure altimeter.