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As I was flying back to Philly from Frankfurt on Lufthansa’s A340, I wondered how fast we are flying. Using time and distance to left to get to destination, I figured a paltry 385 mph. Is this it?
Your speed that you calculated is speed relative to ground and an average over the entire trip. If you experienced strong headwinds, this would affect it. Also, the plane wouldn't travel at max cruising speed from tarmac to tarmac so you would need to take into consideration the initial climb to altitude and the decent to the destination where the plane is flying slower for an extended period of time.
As mentioned above, block speed (gate-to-gate) is less than actual cruise speed.
This time of the year the jet stream may be howling out of the northwest or west resulting in significant headwinds that affect groundspeed. How fast an aircraft goes through the air (true airspeed) minus the headwind component of the winds aloft equals groundspeed.
Faster aircraft are less affected by the headwinds as a percentage of their no-wind cruise speed than slower aircraft. example: Years ago I flew a Piper Arrow, cruise speed of 140 knots, with about 40 knots of headwind, for a miserably slow 100-105 knot groundspeed. More recently a 25 knot headwind and a 110 knot true airspeed in an older Cessna 172 meant a groundspeed not much faster than the highway traffic underneath me on I-44. When I flew the A-10 across the Atlantic from the Azores to NC a 300 knot true airspeed was reduced to 220-230 with 70 knots of headwind. Which sucks, sitting there for 9+ hours. Even fast movers (airliners, private/corporate jets, fighter aircraft such as F-16) are affected when 100 knots+ of headwind are present. [Note knots to mph, multiply by 1.15]
About twenty years ago I flew from Frankfurt to DFW and it took about 10:15; the return flight listed a time en route of 9:30. So those jets streams can not only slow you down but they can make for shorter flights. Airlines even plan for this; look at non-stops to/from east-west destinations. I looked at Southwest's site; Las Vegas-Kansas City is 3:10 westbound (into the prevailing winds) and 2:40 eastbound (with the prevailing winds) this week (mid-January) but in June the westbound flight is 2:55, when the winds are generally much lighter at altitude.
As I was flying back to Philly from Frankfurt on Lufthansa’s A340, I wondered how fast we are flying. Using time and distance to left to get to destination, I figured a paltry 385 mph. Is this it?
There has been a 160-180 knot headwind going west with the Jetstream.
Also keep in mind you have to climb, turn on course and descend which takes more time. Also Philly is a cluster and could add 10-25 mins of time depending on what runways they are landing.
Not sure how Lufthansa displays the time/distance remaining but I'm guessing it was a direct line, and airplanes don't fly direct unless you're flying at 3 AM over central Montana. Flying on the north Atlantic tracks you have to go on specific routes. This adds time as well.
There has been a 160-180 knot headwind going west with the Jetstream.
Also keep in mind you have to climb, turn on course and descend which takes more time. Also Philly is a cluster and could add 10-25 mins of time depending on what runways they are landing.
Not sure how Lufthansa displays the time/distance remaining but I'm guessing it was a direct line, and airplanes don't fly direct unless you're flying at 3 AM over central Montana. Flying on the north Atlantic tracks you have to go on specific routes. This adds time as well.
Going the other way would be a lot quicker.
I have seen it work that way as well. In an F-16 with no external stores speed restrictions, 0.93 mach at 30K and a 100 knot jet stream, I've seen groundspeeds of 650 knots (750 mph). Not bad.
What most people don't realize is that any time a wind is blowing, unless it's a direct crosswind, a round-trip between two points, flying the identical ground track, will take longer than a no-wind trip between the same two points. I'll let y'all stew on that for a while.
Location: About 10 miles north of Pittsburgh International
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Quote:
What most people don't realize is that any time a wind is blowing, unless
it's a direct crosswind, a round-trip between two points, flying the identical
ground track, will take longer than a no-wind trip between the same two points.
I'll let y'all stew on that for a while.
I know why. But I won't give it away. I'll add to the confusion by contributing that, of all the possibilities; no wind,
less than direct crosswind, and direct crosswind, the direct crosswind trip will take the longest.
(The speed is represented by the "feathers" on the wind arrow. Solid triangles are 50 knots, single line is 10 knots, half line is 5 knots. Add them up for total.)
If you fly headwind into the jetstream, do you experience any turbulence?
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