Preferrential Treatment to Southwest

[Lowlevel]

I know a guy who was below 10,000 feet indicating 245 knots, Southwest was also below 10,000 feet and behind the guy I know. The guy was slowed to 210 to allow Southwest in.

We can efficiently do things Mike. Even made a comment we can take a tight turn yesterday from downwind to final yesterday, but they had to let the corndogs in. Usually, it doesn't bug me but when I am vectored on a 20 mile final when I am already late and trying to get home, it breaks the straw on the camels back.

A few weeks ago we were flying BOS-BWI and caught up to a SWA flight flying PVD-BWI. We were doing .81 and he was doing .74 at the same altitude (34K I think). The controller made us slow to .74 or less and follow him (5 miles in trail) all the way to BWI and down the final. We could have easily got a vector around him and passed him, but they would not do that. I still don't know why he was going so slow.

 

[ppragman]

Do you not trust your V speeds either?

When the engineering data, which has a margin of error built into it, says you're ok, you're supposed to be ok.

At ace a lot of times we weren't sure if the ground crew had given us reliable cargo weights, so not always no. Plus, if its icing on the ground, and you've gotten deiced and you're taxiing to go and its still icing, I'd always add a little bit to my speeds, can't hurt, and the runways are long anyhow. However, the engineering data might not necessarily have any margin of error built into it, you've got no way to know, so I usually don't trust it farther than what is logical, if you're getting a clearance to land on a 2000' runway in a 737 there's no point in pushing the envelope, wait five minutes and go to a better runway, it just seems to me that by trying to be efficient they costed the company millions and killed a little kid. You can "get er done," with out being a dumbass, just because the computer says its alright doesn't mean its prudent.

 

[SoCalAprch]

I always hear people talking about this but have not really noticed it. Always hear them asking for shortcuts and most of the time they get them. However most of the time when we ask we get them too. Coming into CMH we got turned in front of Southwest that was on a long final and they were told to slow to final approach speed early for it. So I dunno man. They have tons of flights and chances are if someone is getting put in front of you its going to be southwest just based on the numbers.

 

[kellwolf]

Do you not trust your V speeds either?

When the engineering data, which has a margin of error built into it, says you're ok, you're supposed to be ok.

Except I know what parameters the engineers (who don't fly the airplane) used to determine our contaminated landing charts. I add an extra 1000 ft at least. I mean, thrust reversers 100% at touchdown? THAT'S realistic. Takes a bit for those things to spool up, ya know.

 

[jtrain609]

The engineering data has margins of error built into it, Steve. I don't have a copy of the FAR's to drag out all the certification criteria in part 25, but it's in there.

What are you going to tell me next? That the TERPS assumes you'll fly perfectly and doesn't provide for a margin of error on approach?

EDIT: In fact here it is in 25.111.

Net takeoff flight path - "The actual gross takeoff flight path of an aircraft as determined during certification trails and reduced by a factor up 0.8% for twin-engine aircraft. This fudge factor is built in to assure that a crew with average flying skills and average aircraft performance will achieve at least the net takeoff flight path or better. Net takeoff flight path is used to determine regulatory compliance with required climb gradients. Actual flight path is determined during certification. Net takeoff flight path is the actual flight path reduced by 0.8%. Net takeoff flight path must also allow the aircraft to clear all obstacles by 35 feet vertically, or by 200 feet horizontally with the airport boundries to 300 feet horizontally after passing the airport boundaries. Takeoff flight path beings at 35 feet above the takeoff surface. Takeoff path beings from a standing start and extends to at least 1500 feet above the surface."

Everything explained for the professional pilot - page 158

 

[derg]

And the braking characteristics of the MD80 are such that it's lucky they ever stop on the runway in the first place!

True about the MD-80's.

Overall, reverse thrust is a lot of noise, a lot of drama and a barely discernible amount of braking authority.

Most places in Europe disallow you from using anything over idle reverse and with autobrakes, you really don't notice much of a difference.

 

[jtrain609]

At ace a lot of times we weren't sure if the ground crew had given us reliable cargo weights, so not always no. Plus, if its icing on the ground, and you've gotten deiced and you're taxiing to go and its still icing, I'd always add a little bit to my speeds, can't hurt, and the runways are long anyhow. However, the engineering data might not necessarily have any margin of error built into it, you've got no way to know, so I usually don't trust it farther than what is logical, if you're getting a clearance to land on a 2000' runway in a 737 there's no point in pushing the envelope, wait five minutes and go to a better runway, it just seems to me that by trying to be efficient they costed the company millions and killed a little kid. You can "get er done," with out being a dumbass, just because the computer says its alright doesn't mean its prudent.

Actually we do know that the engineering data has a margin of error built into it; see my post above this one for the citation.

Further, if you know you're not being given reliable weights, why in the world are you taking off? At Amflight all the planes had scales in the back and if the pilot didn't think you were given accurate weights at an out station, you weighed the cargo. I don't know if guys did, but they had the scales to do it.

The problem with the Southwest incident, and the 9E incident up in TVC was that they were not given accurate information on what the runway conditions were.

 

[OldTownPilot]

True about the MD-80's.

Overall, reverse thrust is a lot of noise, a lot of drama and a barely discernible amount of braking authority.

Most places in Europe disallow you from using anything over idle reverse and with autobrakes, you really don't notice much of a difference.

And in some airplanes autobrakes set a rate of deceleration, not brake application pressure, so TRs or not, you will be landing in the same distance. And if you have carbon brakes, you'll put the same wear on the carbon brakes, and increased wear on the TR's.

 

[derg]

Two points for the man from Bangor!

Absolutely correct.

 

[SoCalAprch]

In our ERJs the brakes can be grabby if you get on them right when you touch down. Ive found that applying a little reverse thrust and then bringing in the brakes once you have slowed a bit really helps with the jerkiness. But granted that's just in the little ERJ and every plane is different. I'd like to see a comparison of how much longer brakes will last when using the reversers compared to not and how much money in fuel is saved over the life span of the brakes if you don't use the reverse thrust.

 

[derg]

Opinion only and I'm not an aeronautical engineer so take what I have to say with a grain of salt, but if reverse thrust was a significant factor in landing distances, manufacturers would predicate performance on their usage.

 

[Maximilian_Jenius]

And in some airplanes autobrakes set a rate of deceleration, not brake application pressure, so TRs or not, you will be landing in the same distance. And if you have carbon brakes, you'll put the same wear on the carbon brakes, and increased wear on the TR's.

Two points for the man from Bangor!

Absolutely correct.

...yea, but it sounds and looks cool!

 

[mikecweb]

Real men fly planes with a drag chute.

 

[kellwolf]

Certain stuff, I rely on. Things like V1 cuts, single engine climb, etc, I know the airplane will do. But things like stall buffet charts. It even says in our manuals that the data the charts are based off will not be acurate during normal operations. The contaminated landing charts were rushed out in 2006 by the FAA. The NTSB was a little miffed that they went around the standard practice, but the public needed to see something after the SWA Midway accident. Some airlines already had charts in place, but some didn't. I know mine didn't b/c they rushed the charts out when I was an FO. The data used to generate the charts is pretty unrealistic as well. On speed, cross the threshold at 50 feet at flight idle, and touchdown on the 1000 ft markers. Okay, that I can go with. TR deploying to 100% on touchdown? Not gonna happen. It's gonna take a couple of seconds for those babies to spool up. There went that 15% margin the FAA requires.

 

[Baronman]

Opinion only and I'm not an aeronautical engineer so take what I have to say with a grain of salt, but if reverse thrust was a significant factor in landing distances, manufacturers would predicate performance on their usage.

True...maybe it would be very difficult for the manufacturer to quantify their effectiveness or to create good data based on varying conditions. Also, when they're deployed could effect the numbers. I know the ERJ has a little different system as it related to the thrust levers/reversers. We basically take our thrust levers back over a detent that only becomes available with weight on wheels. Sometimes it can get a little "stuck" resulting in a least a 1 or 2 second delay.

I think that they're (TRs) very effective in the ERJ. Even in idle you decelerate...I really don't know how they are alone without brakes in max because I've never not applied the brakes with them. And really it's been a couple months since I've spooled them up.

Ahh..and getting back to SW. Maybe we just seem to notice it more when SW gets a favor, or maybe it's just that they ask for more favors but I'm a believer that they DO get special treatment. Just my opinion.

 

[kellwolf]

Opinion only and I'm not an aeronautical engineer so take what I have to say with a grain of salt, but if reverse thrust was a significant factor in landing distances, manufacturers would predicate performance on their usage.

Without TR data, we wouldn't be flying to places like AZO, TVC or ERI in the winter. I don't know how they came up with the numbers to do it before the contaminated charts came out. Now, on a normal, dry runway, no problem. If you've got compacted snow and fair braking, chart says you're not landing on 18/36 in TVC, and that's WITH TRs going. You'll stop with the runway 10 feet behind you according to the chart.

 

[SpiceWeasel]

TR deploying to 100% on touchdown? Not gonna happen. It's gonna take a couple of seconds for those babies to spool up. There went that 15% margin the FAA requires.

I can never get the little click-locks to release right away either.

Any suggestions ?

 

[SteveC]

I can never get the little click-locks to release right away either.

Any suggestions ?

Well, if they're interlocked with the squat switches you might try getting her on the ground before you open the buckets.

 

[SpiceWeasel]

Well, if they're interlocked with the squat switches you might try getting her on the ground before you open the buckets.

heh Well dang I always thought that it was a lot more efficient to try and use the reversers instead of the speed brakes if I was trying to make a steep but speed restricted descent.

 

[kellwolf]

Well, if they're interlocked with the squat switches you might try getting her on the ground before you open the buckets.

Hey, us fancy 121 drivers call those Weight on Wheels detectors.

And yeah, they're tied in. In the sim, you can click 'em, count to three, then pull 'em. Not so much in the real airplane. I generally just push 'em in and hold 'em until they click. Might be different on that fancy-pants -900, though.