New York to Los Angeles: the transcon and the Rockies
- Departure
- John F. Kennedy International Airport, New York, the United States
- Arrival
- Los Angeles International Airport, Los Angeles, the United States
- Great-circle distance
- 3,974 km (2,146 nm)
- Typical airborne time
- 5h 07m
- Usual cruise levels
- FL330 to FL390
- Initial track
- westbound
Route overview
New York JFK to Los Angeles is the classic American transcontinental, flown daily by Delta, American, JetBlue Mint and United. Westbound it usually takes around six hours, eastbound closer to five, because the prevailing winds across the country blow from west to east. Cruise altitude typically sits between FL340 and FL400. The interesting piece of geography on this route is not the coasts but what sits in the middle: the Rocky Mountains.
Why turbulence happens on this route
For roughly the first third of the flight, you are over the flat interior of the country, and the ride is normally smooth. The signature bump on JFK-LAX comes mid-flight, when we pass over the Rockies. When strong westerly winds hit a big mountain range, the air on the downwind side ripples up and down like water flowing over rocks. Pilots call this a mountain wave, and it can extend tens of thousands of feet into the atmosphere, well up to our cruise altitude. In winter these waves are more common and more intense because the jet stream often sits right over the range. In summer they are usually mild or absent. The other thing to know is that thunderstorms can build over the Rockies and the desert southwest in the warmer months, and we simply route around them. Nothing on this corridor is a mystery to our dispatch and crew.
Which seasons are bumpiest
Late autumn through early spring, roughly November through March, is the season when mountain-wave activity across the Rockies is strongest, because the winter westerlies are at their peak. Summer brings the opposite kind of concern: convective weather, meaning thunderstorms, which we see clearly on radar and route around. September and October are often the smoothest months of the year on this route. Even in a bumpy winter westbound cruise, the flight remains completely safe. The seat belt sign is the tool, and cruise altitude adjustments are routine.
How pilots handle it
Before we push back, our dispatch reviews wind and turbulence forecasts across the Rockies and picks an altitude that avoids the worst of the wave activity. In the cruise, if we start to feel wave-driven ripple, we usually ask Denver or Salt Lake for a different flight level, since a few thousand feet up or down often changes the ride completely. If thunderstorms are forecast over the desert southwest, we adjust our track by tens or even hundreds of miles to give them a wide berth. On the ground, before the descent into LAX, we brief the arrival carefully because the Pacific marine layer and terrain around Los Angeles both need attention. It is straightforward work our crews do every day.
What you can do as a passenger
This is a great daytime flight to watch out the window, because you get to see the country change from forests to plains to mountains to desert. Pick a window seat over the wing for the most stable ride and the best photos. Keep your seat belt fastened when seated, drink water, and moderate the caffeine and alcohol. If mountain-wave chop shows up mid-flight, remember it is a pattern of air, not a problem with the aircraft, and it usually passes within minutes. A downloaded playlist or show helps the time fly.