Why are taxi-ways parallel to runways?

Any airport designers in the house?

I was reading this BBC article and this Pprune thread and remembered that Harrison Ford made a similar mistake. In both instances the taxi-way was parallel to the runway. I believe that’s normal practice. Why is this? Would it not be safer for taxi-ways to be at an angle to the main runways?

Efficiency, cost, space.

nm

The taxiway needs to go to both ends of the runway, to send planes out to be launched and to recover planes that have landed. How else would you make one long straight thing go to both ends of another long straight thing, other than making them parallel?

Not only that, but some planes don’t need the entire runway to land. With a parallel taxiway you can have several turn-offs, and not waste valuable runway time waiting for that little commuter plane to get all the way to the end of a 2.5 mile long runway before turning.

Because maybe it might be better as two shorter, angled, things instead of one long straight thing?

I’m wondering how the Air Canada pilot managed to get aligned with the the taxiway unless he was ignoring the instruments. Don’t they use ILS anymore?

Can’t they (don’t they?) just use a different paint and lighting scheme to make it obvious whether you’re on the runway or the taxi-way? And, if they already do this but there is still confusion, just make the paint and lighting schemes that much more obvious and distinctive.

They are not absolutely always parallel end-to-end, just that at the vast majority of locations that is the most space- and traffic- efficient lay-out. If space is tight and flow is not heavy, you are more likely to just not have it all the way from end to end, but runway accesses part-way down its length and then a turnaround spot at the far end(s).

But then you’re adding length, which adds to cost, and each aircraft takes a little bit longer to make the trip. Also, your mid-field turnoffs will be longer and more expensive.

They do, but paint fades and lights burn out. Taxiways and runways have different color edge lights and centerline lights, when they exist.

The FAA has updated marking methods in the last few years as part of an effort to reduce runway incursions (airplanes being there when they shouldn’t). But only the busiest airports get the flashing lights, while the lower-budget ones settle for paint stripes.

Most airports in the US are the small, general-aviation type. Out of 13,000 or so, only about 500 have airline service, for instance, and only about that many have control towers. Most have much tighter budgets, and much less of a safety problem.

Would a functional ILS show the pilot he was on the wrong track? If so, what happened here?

This is why we need the circular runways which were mooted recently :stuck_out_tongue:

[QUOTE=ElvisL1ves]
The FAA has updated marking methods in the last few years as part of an effort to reduce runway incursions (airplanes being there when they shouldn’t). But only the busiest airports get the flashing lights, while the lower-budget ones settle for paint stripes.
[/QUOTE]

SFO is pretty busy. I’d like to think they had the updated markings/lights. Even at midnight, the difference between a runway and an adjacent taxiway should be pretty obvious.

Taxiway lights are blue and runway lights are white. One hypothesis that’s been offered is that the Air Canada pilot in yesterday’s event saw the white forward-facing lights of four jets lined up on the taxiway and lined up on them in error. Think someone’s grasping at straws there - this photo shows a typical runway’s lighting and to the left, the blue lights of a taxiway.

Sure they do, but it’s not available on all runways. Other types of approaches might or might not be available too. But I’d bet some money that the incident at SFO happened during a visual approach.

I’m a charter pilot, and I’ve been in this situation many times:

The weather is good, airport information is calling visual approaches to runway 28 Right. Looking at my direction of flight, I see it will probably be a straight-in. Next thing I look for is an instrument approach to that runway. Even if I’m doing a visual, I can try* to back it up with the ILS.

Maybe that runway doesn’t have an ILS, or any other approach I can use. Or maybe it does, and it’s out of service. In those cases, maybe my airplane’s avionics can create a glide path on it’s own, maybe it can’t. Let’s say I’m flying something older and it can’t do that, and it’s going to be all me. I look at the airport elevation, my current altitude and distance, do a little figuring and fly based on what I see out the windshield. Hopefully I am thinking far enough ahead that I fly to the correct runway, and double check a few things to ensure it. This happens all the time, even at major airports.

No idea if that’s what happened to Air Canada. But again, I’m betting this was some sort of visual approach gone awry.

  • Even if there is an ILS available, I might not be in a good position to utilize it. If I’m coming from the other side of the approach, effectively flying a downwind, I’m probably going to turn base inside of the final approach fix. That means I won’t have the glideslope, at least not from it’s initiation point. You can pick it up on the way down, but it’s not as easy as just flying it from the FAF. Or the controller might vector me in such a way that I’m not in position to use the glideslope and again, it’s all on me.

Once, going into a towered airport in a jet, I had a controller send me (in visual conditions) over the top of the airport. I had already called it in sight, but he had other traffic. Once his traffic was clear he asked if I still had the field in sight. I said yes, and he said, “Cleared visual.” Thanks a lot - I’m now 5000’ directly above the airport, and the landing runway is just behind my tail. That’s a situation where the controller has basically relinquished all responsibility and said, ‘go figure it out yourself’.

It was 11:55PM. Do Visual Flight Rules work at midnight?

Not available on all runways? You mean in rural cowtowns like SF? Wasn’t ILS first implemented in the 1960’s? Wasn’t one of the primary purposes of ILS to avoid accidents like this one?

Yes but Ford would have certainly been flying VFR. My GPS software will draw a line right down center of any runway regardless of the approach system but at some point the pilot is focused on flying the plane.

Sure they do, you can do a visual approach at night. But some airlines, such as the one I used to fly for, had a rule that you had to have some sort of glideslope at night. As I said, I don’t know what exactly happened at SFO. We’ll see, but I’m betting visual.

And just because it’s a major airport, that doesn’t mean an ILS is going to be available on all runways at all times. I’ve done visual approaches at SFO, JFK, BOS and various other big airports for multiple reasons. There is an ILS on 28 R at SFO, so we’ll see what comes out of this. Maybe it had little to do with visual conditions, and it was an FMS programming error.

E’s Canadian, Eh? Lettin’ someone else go first, ya know?

And some places provide the “exception to prove the rule”. Look at this diagram of Buchanan Field, Concord, CA (KCCR). The long black lines are the runways. The taxiways are in gray and labeled with letters.