JAL - Why is NRT-DEL 2.5 hours longer than DEL-NRT?
 

Firstly, apologies for asking a question that may well be better placed at kiddiestalkingaboutairlplanes.net.

Secondly, perhaps this would be more appropriately placed in the JAL forum, but I think this forum has a wider audience and more likely to get an answer.

Looking at the schedules, NRT-DEL-NRT is non stop yet the outbound dayflight has a 10:00 scheduled flight time. The return overnight flight only has a scheduled duration of 07:25.

What is the reasoning for such a difference in duration for a sub-4000 mile flight? :confused:

I initially thought it maybe due to crossing restricted airspaces, but that doesn't explain the shorter return leg. Winds could be another reason, but surely not that favourable?

Maybe. In April the difference goes down substantially.

The "jetstream" winds often have quite an effect. It more in relation to East/West travel than North/South.

e.g. Qantas schedule their 743's SYD to PER duration for 4:45 and 4:00 hours on the return. NZ schedule their AKL-PER flights at 7:35 and 6:25, 1:10 less on the return.

NRT is ~63° east of DEL & 7° North, so it's quite the latitudinal route.

Of course, there would be other locality related issues; but not as significant methinks.

Two years ago SYD-JNB took us almost 15 hours. Last year JNB-SYD took right on 11 hours, almost 100 kts faster average ground speed.

And the answer is ... the absurd runway situation at NRT. The extra time is taxi/wait time for getting off the ground at NRT. Typically 30+ minutes delay. Inbound gets priority so does not suffer from the same delay. JL got tired of having a late arrival into DEL so they incorporated this (accurately) into their schedules. The rest of the difference is due to winds, of course, which does amount to almost 2 hours for a 3679 mile flight. The rest is NRT airport delay.

But the difference is dropping down to 2 hours in a few days... does that mean the NRT runway problem is going to be solved by then?

Maybe a combination of seasonal winds and reduced runway congestion based on flight patterns at time of departure.

I say the former, based on the fact that the difference goes back to 2.5 hrs at the end of this year. It is hard to visualize a runway problem so finely attuned to the seasons.

I'd love BA to build this into their schedules at LHR.

Wind alone can not explain this difference so it must be something runway different as well and number_6's explanation makes a lot of sense.

Scheduled journey times from NRT to SFO are typically two hours shorter than the scheduled times for SFO to NRT.

I'd always assumed this difference was built into the schedule due to the prevailing winds.

But perhaps it's actually because the airlines built in a 2.5 hour cushion for departures from SFO to compensate for delays there?. (and a 0.5 hour delay on the NRT side)....

Nah. I don't think so.

If the runway is what accounts for the difference how come Nort/South fligths, like NRT-SYD do not experience this difference and have the same schedules year round?

NRT-SYD is 9h20m and SYD-NRT is 10h35m. So there is a substantial difference. But it is exactly the opposite of what the OP experienced so it can't be the runway and I would guess this is just the wind.

sdorling, are you sure you have your times right (Tokyo is 3.5 hours ahead of Delhi)? Because I just looked flights up and this is what I got for early April:

NRT-DEL 9h15m DEL-NRT 8h00m

This looks pretty normal to me considering the wind direction on this planet.

This is correct, it is normal, but now look at the winter timetable, which is what sdorling must have been seeing, and you will find that in winter the difference goes way up, to the reported 2.5 hrs.

NRT-SYD has ~660 miles of easterly travel so there's 40 minutes difference with the return. As stated, other factors make up the rest.

I was going to post that Daylight Savings fitted nicely into this problem until I saw this:
http://webexhibits.org/daylightsaving/g.html
:confused: