Moderator: Hawaii-Based Airlines, Travel with Children & United Mileage Plus
Join Date: Mar 2003
Location: Lost in the Bermuda Triangle
Programs: G1 Offender - Platinum Level
Posts: 7,517
Ground Ops Questions
Is there a "speed limit" while taxiing? I've been on a few WN flights were, after landing on 24L or R at LAX, we've sped back to Terminal 1 at a rate far more than the normal rate (I'm guessing 10-15 mph is the standard). They even deployed the thrust reversers to slow us down.
This is probably a "no" for the heavy and low-engine pilots, but have you ever used reverse thrust to back from the gate; I've been on an AA MD-80 where they did that.
__________________
Remembering 61 Years of Service - Mahalo Nui Loa, Aloha Airlines
Yesterday, I heard a pilot tell ATC that due to operational restrictions, they could not go above 33000 feet and .75 mach, and to pass that information along.
Aside from physical limitations, what could cause a plane to have to follow such restrictions?
Programs: AS MVP (withering away due to insane fares), UA, AA, AGR, NPS passport, Costco Exec
Posts: 5,241
Quote:
Originally Posted by aluminumdriver
I think metering has been covered before in this thread if you search it. Basically, at very busy airports there is a seperate ground freq, called metering. You call them when you are ready to taxi and they put in the que for ground control. You monitor ground control freq and they call you when they are ready for you. Just a way of keeping radio traffic to a minimum on a busy ground control.
Mountain wave is turbulence coming off a mountain range (usually the Rockies in the US). Think of them as rolling eddies of air, and when you are in them your plane goes up and down these little waves. Most of the time they are not too bad, but if you are low and coming over the mountains, it can get pretty bumpy. We search out the smoothest altitudes to come across the ranges while missing the waves. It can be higher or lower than our planned altitudes, we just listen to dispatch or PIREPS from other planes to seek out the smoothest rides.
Before someone asks it, PIREPS are "PIlot REPortS"--exactly what they sound like (pilots will report the conditions they observe to ATC, who then files them and can distribute them to other aircraft or in pre-flight briefings).
Is metering the same thing as (i.e. another name for) clearance delivery?
Is there a "speed limit" while taxiing? I've been on a few WN flights were, after landing on 24L or R at LAX, we've sped back to Terminal 1 at a rate far more than the normal rate (I'm guessing 10-15 mph is the standard). They even deployed the thrust reversers to slow us down.
Even at normal taxi, people often underestimate the speeds, because planes are so large they seem to go slow. But actually typical speeds are like 25 mph (was told to me, not my own knowledge).
Go arounds happen all the time, but I don't think I've experienced the use of an S turn (didn't go too far in either direction) before, its usually a request to reduce speed.
I agree with AD that it was likely traffic on the intersecting runway unable to hold short. The only piece I wanted to add is that ATC cannot issue a speed assignment inside of the final approach fix (about 5 miles from landing). They can ask you to "slow to final approach speed" or do S-turns, but can't assign a specific speed.
I'm not a big fan of S-turns, since they are either generally ineffective, or if done well enough to be effective, tend to destabilize the approach and cause concern among the passengers.
Quote:
I had an awesome crew tonight on my connecting flight, when I went up to say hello and ask if they'd have channel 9 available (yes), the captain invited me into the cockpit and asked if I had any questions. It totally caught me off guard so I couldn't come up with any of the many I thought of later, but did ask about this. The FO even offered me his seat while he was doing his walk around (didn't take him up on it this time though).
Wow, the bar is pretty low if that's what makes an awesome crew! We do this all the time, but most of the time people take me up on the offer to have my seat. In fact, I usually tell them that if they can start the airplane, they can have it (no one has figured it out yet).
Quote:
Originally Posted by dimramon
Yesterday, I heard a pilot tell ATC that due to operational restrictions, they could not go above 33000 feet and .75 mach, and to pass that information along.
Aside from physical limitations, what could cause a plane to have to follow such restrictions?
Quote:
Originally Posted by FortFun
Check out posts 893/894 of this thread for starters (page 60 at the default posts/page setting).
May be discussed elsewhere as well, I can't remember.
It's unlikely to be the reason discussed in those posts (basically being too heavy). Since it was presented as an operational restriction to ATC, my assumption is that there was a maintenance issue preventing higher altitudes and/or speeds. Altitude restrictions are generally due to air conditioning pack limitations (pressurization), but that wouldn't necessarily limit the speed. It could simply be that it was an older 737 and mach .75 was the best they could do at 33,000.
Quote:
Originally Posted by jackal
Is metering the same thing as (i.e. another name for) clearance delivery?
No. Route clearances are given on clearance delivery (imagine that!), while metering is used to indicate you are ready for taxi without tying up the ground control frequency. We almost never talk to clearance delivery anymore since we get our clearances over ACARS, except when there's a problem or a change. ORD is the only place where metering is consistently used, although it occasionally pops up at LAX (maybe IAD?).
I agree with AD that it was likely traffic on the intersecting runway unable to hold short. The only piece I wanted to add is that ATC cannot issue a speed assignment inside of the final approach fix (about 5 miles from landing). They can ask you to "slow to final approach speed" or do S-turns, but can't assign a specific speed.
I'm not a big fan of S-turns, since they are either generally ineffective, or if done well enough to be effective, tend to destabilize the approach and cause concern among the passengers.
I was on a 777 flight a few years ago into DEN (from SFO) and I believe our pilot actually requested the S turns himself. I think they said they had an issue getting their speed down. It did feel like the descent was destabilized. In fact, as we got closer, the pilot requested the ##R runway instead of the active ##L runway. Apparently ATC opened R just for our flight. I'm assuming this was due to a combination of being a heavy, DEN altitude, and prevailing winds. Any insight?
I was on a 777 flight a few years ago into DEN (from SFO) and I believe our pilot actually requested the S turns himself. I think they said they had an issue getting their speed down. It did feel like the descent was destabilized. In fact, as we got closer, the pilot requested the ##R runway instead of the active ##L runway. Apparently ATC opened R just for our flight. I'm assuming this was due to a combination of being a heavy, DEN altitude, and prevailing winds. Any insight?
Denver used to be terrible about keeping you high and fast, but it's gotten better in recent years (mostly due to feedback from safety programs). I've also done pilot initiated S-turns, along with all the normal things to stabilize the approach. Visually we need to be stabilized by 500', or a go around is required.
To appease the other passengers in case you got it wrong, I'd just ask you to point it out. Do you think you could do it?
Which aircraft? I hope it's not a 777 because there's a big "autostart" button on the overhead panel which really takes away the challenge. I regularly start a Piper Arrow after the engine is hot, and I figure if I can do that... (you know, throttle full open and mixture full cutoff, and when through divination and other voodoo you detect that the engine might catch, you immediately reverse the two levers as fast as you can..)
The basic procedure seems common to all jets. Find a source of air (we'll ignore jets with generators that double as electric starters) - usually the APU - and get that air flowing to the engine you want to start. Wait for the appropriate N1 (20% or so?) and flip the fuel lever forward. Watch the gauges to make sure the engine doesn't start to burn up. The rest of the overhead panel procedure consists of turning all the amber lights green. With an abnormal start I'm not sure I would know what to do other than shut it down and try again.
I can confidently say that I could do it on a 737, because I have practice. A 757 I've started up only in a Microsoft simulator, and I did find that challenging without any instructions.. my mistake was leaving air going to the PACKs and apparently there wasn't enough pressure to get the engine going. At least the computer didn't think so. I've never even looked at an Airbus.. but those pushbuttons are not as intuitive as mechanical switches!
Which aircraft? I hope it's not a 777 because there's a big "autostart" button on the overhead panel which really takes away the challenge. I regularly start a Piper Arrow after the engine is hot, and I figure if I can do that... (you know, throttle full open and mixture full cutoff, and when through divination and other voodoo you detect that the engine might catch, you immediately reverse the two levers as fast as you can..)
The basic procedure seems common to all jets. Find a source of air (we'll ignore jets with generators that double as electric starters) - usually the APU - and get that air flowing to the engine you want to start. Wait for the appropriate N1 (20% or so?) and flip the fuel lever forward. Watch the gauges to make sure the engine doesn't start to burn up. The rest of the overhead panel procedure consists of turning all the amber lights green. With an abnormal start I'm not sure I would know what to do other than shut it down and try again.
I can confidently say that I could do it on a 737, because I have practice. A 757 I've started up only in a Microsoft simulator, and I did find that challenging without any instructions.. my mistake was leaving air going to the PACKs and apparently there wasn't enough pressure to get the engine going. At least the computer didn't think so. I've never even looked at an Airbus.. but those pushbuttons are not as intuitive as mechanical switches!
Small point, but normally you wait to add fuel until you have a minimum N2 rotation, not N1. I've never had a jet where we worried about N1 rotation, only to make sure we have some eventually.
Quote:
Originally Posted by FlyinHawaiian
Is there a "speed limit" while taxiing? I've been on a few WN flights were, after landing on 24L or R at LAX, we've sped back to Terminal 1 at a rate far more than the normal rate (I'm guessing 10-15 mph is the standard). They even deployed the thrust reversers to slow us down.
This is probably a "no" for the heavy and low-engine pilots, but have you ever used reverse thrust to back from the gate; I've been on an AA MD-80 where they did that.
Taxi speed is really the speed safe for that area of the airport. SWA guys seem to taxi around at speeds just prior to rotate speed Most others want to keep a safe speed where we can stop quickly if need be without sending the flight attendants into the left corner pocket. We do have maximum speeds for exiting the runway and sharp turns, but that's about it.
I've never used thrust reversers to taxi or back away from the gate since all of United's jets are wing mounted engines. We are forbidden from using thrust reversers to back up the jet and have to be at idle forward thrust by 60 knots on the runway landing. The reversers on the 80 and -9 are clam shell reversers, so they are better for backing up. The problem with wing mounted engines at slow speed with reversers on is you are at a very good chance for fodding out the engine versus up high on tail mounted ones. But, the main reason we don't do it is our flight manual prohibits it.
__________________
These views are my own and do not represent the views of United Airlines or the ALPA.
Last edited by aluminumdriver; May 22, 08 at 9:25 pm.
Programs: UA 1K (3K), Hilton Diamond, National EAEE
Posts: 1,291
Quote:
Originally Posted by aluminumdriver
Most others want to keep a safe speed where we can stop quickly if need be without sending the flight attendants into the left corner pocket.
ROTFL!!
Quote:
Originally Posted by aluminumdriver
I've never used thrust reversers to taxi or back away from the gate since all of United's jets are wing mounted engines. We are forbidden from using thrust reversers to back up the jet and have to be at idle forward thrust by 60 knots on the runway landing. The reversers on the 80 and -9 are clam shell reversers, so they are better for backing up. The problem with wing mounted engines at slow speed with reversers on is you are at a very good chance for fodding out the engine versus up high on tail mounted ones. But, the main reason we don't do it is our flight manual prohibits it.
Ahh... only time I had this happen was in a Fokker (something) and we backed out of a tight corner gate. I was amazed they were allowed to do that!
Going back to mountain waves, I was in one when we were just west of Denver. I heard the crew report it to ATC on Ch. 9 and I knew just what it was having experienced it. Its like being in a gentle roller coaster, up and down, up and down... repeat...
One question... one time I was flying a redeye SEA-IAD and somewhere over the west I was awoken when we got caught in what I would call a vortex. We were riding right down the jet stream with a tailwind and I think we got caught right in it. It started translating us in a circle around the direction of flight pretty quickly and it kept going. Shortly the crew appeared to try and get us out of it by descending but seemed to take some effort and they were trying to do it gently. Eventually it died off after a couple minutes and they got us down a bit. Any of you pilots ever experience that?
Programs: UA-1K MM, Priority Club Platinum, Avis First, Hertz Gold, Red Lion
Posts: 893
EMB 120 operational limits
After a bad experience on takeoff from SFO on Tuesday (high winds...30 knots with higher gusts), what are the cross or headwind limits for takeoff on the EMB 120. I detailed my experience here.
I guess I would like to regain confidence in the equipment as I used to think they were pretty good in weather but this was really really bad for me (and I fly them a lot...40-50 flights a year).
__________________
channel 9...more than tower communication...it brings flights to life!
Which aircraft? I hope it's not a 777 because there's a big "autostart" button on the overhead panel which really takes away the challenge.
I do fly the 777, but you'll have to do better than that. There is no autostart button, for starters. There is an autostart panel, but simply moving those switches won't get you an engine started. First, you've got to start the APU.... and even then, the autostart panel won't get you a running engine...
Quote:
The basic procedure seems common to all jets. Find a source of air (we'll ignore jets with generators that double as electric starters) - usually the APU - and get that air flowing to the engine you want to start.
The devil is in the details. How do you start the APU? How do you get the air flowing to the starters?
Quote:
Wait for the appropriate N1 (20% or so?) and flip the fuel lever forward.
On all United's airplanes but the 777 and the A319/A320, you wait until max motoring of N2 (not N1), defined as less than a 1% N2 rise per second (I count to five when it slows down and watch to see how fast N2 rises) - in all cases it needs to be above minimum motoring N2.
Quote:
I can confidently say that I could do it on a 737, because I have practice. A 757 I've started up only in a Microsoft simulator, and I did find that challenging without any instructions.. my mistake was leaving air going to the PACKs and apparently there wasn't enough pressure to get the engine going. At least the computer didn't think so. I've never even looked at an Airbus.. but those pushbuttons are not as intuitive as mechanical switches!
You've got close enough that you should hope you get to fly with me. You might get yourself a slightly used 777.
Most others want to keep a safe speed where we can stop quickly if need be without sending the flight attendants into the left corner pocket. We do have maximum speeds for exiting the runway and sharp turns, but that's about it.
