I find it hard to believe how slow it takes a 737-800/900 to get to 35,000ft with a full load. I posted this is the FSX forum but it may have come across as trying to get two add-ons to complete. I'm just trying to see if what I'm seeing in FS9 with the 737-800 matches real world performance. I'm at work so I can't give accurate numbers as to passenger/baggage load but last night I was looking at this in comparison to my 757/A320 flying I've been doing as of late. I had a full load of passengers with a 100% fuel in each tank at the ramp/gate. I was 700 pounds overweight so I adjusted my fuel in the three tanks to 50% each. From takeoff at KLAX on my way to KIAH it took 45 minutes to reach 39,000ft using 'LVL CHG' all the way up (allowing the AP to adjust best rate of climb where as manually adjusting climb rate would be all but impossible). I had a tail wind of 53kts. In comparison it takes the 757/A320 not much over 20 minutes to get to the same altitude. I can't believe an airliner as popular as the 737-800 has such poor climb performance. I could not find any data online or numbers to go by to confirm what I'm seeing in the sim is comparable to the real world so I thought I'd ask here.

This issue, almost always, is related to the sims OAT. What was your OAT? Which aircraft?

This issue, almost always, is related to the sims OAT. What was your OAT? Which aircraft?

OAT???

 

The aircraft in question is the iFly 737-800 (900 as well).

OAT = Outside Air Temperature

 

If it's too high for some reason it can cause decreace in climb performance.

Depending on temperature and weight the 737 can be a "slow climber" particularly when compared to the 757 which happens to be one of Boeing's best performing designs.  In fact, the 737's max altitude can be FL 33.0 to 35.0 when hot and heavy (check your CRZ page and the MAX and Recommended Altitudes should be displayed).  I've rarely (trying to remember if ever) flown the 737-800 at FL 41.0 and have come to take the maximum displayed by the FMC conservatively, meaning, that at that altitude the jet is slow close to both it's maximum and minimum speed limits that it is uncomfortable to monitor it as a pilot.  Even the recommended FL is usually above what the Company's dispatchers recommend based on their computer modelling which is specific down to the tail number for the jet you're flying.  ( ... and I've found their models are so accurate that I can't beat them by climbing early or higher)

 

Your example is a worst case scenario for any jet.  Climbing into a tail wind reduces relative performance as the airplane must both accelerate through decreasing performance shear and yet climb.   

 

For a nice handling hot-rod, the 757-200 is hard to beat.  As a pilot, I hate to see those jets getting close to the end of their operating lives.  The 737-800 (and 900) does the job efficiently and safely, but it is not anywhere near the airplane the 757 is.

 

P.S.  OAT "Outside Air Temperature" ... warm air is less dense than cold air (which is how a hot air balloon works); warm air means there is less "air" there for the engine to burn and wing to get lift from.  Cold air is to an airplane what a turbocharger is to a car ... I've got no idea how your sim works, but FSX models OAT and should give you better performance when cold, worse when hot.

Depending on temperature and weight the 737 can be a "slow climber" particularly when compared to the 757 which happens to be one of Boeing's best performing designs.  In fact, the 737's max altitude can be FL 33.0 to 35.0 when hot and heavy (check your CRZ page and the MAX and Recommended Altitudes should be displayed).  I've rarely (trying to remember if ever) flown the 737-800 at FL 41.0 and have come to take the maximum displayed by the FMC conservatively, meaning, that at that altitude the jet is slow close to both it's maximum and minimum speed limits that it is uncomfortable to monitor it as a pilot.  Even the recommended FL is usually above what the Company's dispatchers recommend based on their computer modelling which is specific down to the tail number for the jet you're flying.  ( ... and I've found their models are so accurate that I can't beat them by climbing early or higher)

 

Your example is a worst case scenario for any jet.  Climbing into a tail wind reduces relative performance as the airplane must both accelerate through decreasing performance shear and yet climb.   

 

For a nice handling hot-rod, the 757-200 is hard to beat.  As a pilot, I hate to see those jets getting close to the end of their operating lives.  The 737-800 (and 900) does the job efficiently and safely, but it is not anywhere near the airplane the 757 is.

 

P.S.  OAT "Outside Air Temperature" ... warm air is less dense than cold air (which is how a hot air balloon works); warm air means there is less "air" there for the engine to burn and wing to get lift from.  Cold air is to an airplane what a turbocharger is to a car ... I've got no idea how your sim works, but FSX models OAT and should give you better performance when cold, worse when hot.

Thanks for the great post...

 

OAT - I know what it is just making sure we were on the same page. For those that don't know a cold winter day gives better performance than a hot summer day when taking off at your local airfield.

 

757 - I too am sadden by the move away from the 757 (exception being FedEx) in favor of an inferior model. The climb rate in the 737-800/900 sucks. They should at least put more powerful engines on those birds. The 737-700 by contrast is great and has an awesome thrust to weight ratio.

The airlines care about how cheap it is to fly not if the climb rate is thrilling for pilots. Also better fuel planning will help the climb rates.

I've read from some United pilots that the 737-900er is one of the most underpowered airliners in the sky right now.

 

They said on flights from EWR-LAX they take full runway, flaps 5 and bump thrust and they still use a significant amount of runway.

 

I'd love to see Boeing and CFM design an engine with 33K-35K thrust for the 900/900ER.

Keep these comments coming. I'm surprised an airliner with this kind of performance is the alternative for airlines. Can someone explain how throttled up engines taking much longer to get to cruise altitudes is more fuel efficient? You would think an airliner that can efficiently get to cruise without struggle (like the 757) would save fuel. Takeoff and climb burns the most fuel.

 

It's funny I remember seeing a show on the History Channel where they did a piece on KLGA in talking about the MD-80 being a less efficient bird to get off the runway and special care was needed when dealing with that bird. Now we have the much newer -900 more of a problem. You'd think things would progress not degress.

I don't think it is a slouch in the performance department when flown correctly. I've sat in the jumpseat in all of Boeings current offerings besides the 747 and they all got to the mid 30's in the same time. The problem with FSX is that it is not completely accurate in its modeling of flight, fuel burns, and climb performance. One of the 737's I was one even was a flight from Hawaii to the mainland. There were only two empty seats and enough fuel to keep the APU burning the whole flight as well.

I don't think it is a slouch in the performance department when flown correctly. I've sat in the jumpseat in all of Boeings current offerings besides the 747 and they all got to the mid 30's in the same time. The problem with FSX is that it is not completely accurate in its modeling of flight, fuel burns, and climb performance. One of the 737's I was one even was a flight from Hawaii to the mainland. There were only two empty seats and enough fuel to keep the APU burning the whole flight as well.

Allot of things come into play on any particular flight so it's hard to say. I did a flight last night (I use FS9 by the way) and the performance was allot better. Upper level winds were south by south east at 53kts so it was a slight cross wind in the direction I was flying. Much better climb to altitude. I think the point has been nailed down that the NG 800/900 leaves allot to be desired in the thrust department. Climbing out is nice on a cool day, heck even a warm day meaning you can get upwards of around 2,000+ FPM from 10,000ft to 24,000ft. Things get interesting after 27,000ft where you can be around anywhere from 1400fpm to 500fpm (which the manual states is how the real bird performs). As always my hat is off to iFly and PMDG for their depiction of the bird...

I think the point has been nailed down that the NG 800/900 leaves allot to be desired in the thrust department.

 

.../...

 

As always my hat is off to iFly and PMDG for their depiction of the bird...

Not to demean iFly but maybe their flight model is not perfect. It would be interesting to check if simmers using the NGX (for example) obtain similar results.

 

Please note I am not saying the NGX is good and iFly isn't. Just looking for different references.

 

Bruno

 

PS (edit) : Have you checked the PMDG 737 NGX forum? You'll find quite a few RW 737 pilots there that can answer your questions on the matter.

Dillon, do you use http://www.flightradar24.com

 

Best source for gathering real time information, this morning I was tracking a KLM 737-700 climbing out of Schiphol and he was climbing at 3200 fpm up to 10,000 feet, and 2900 fpm through 20,000 feet.

 

At least with that website you can compare the 737-900 to the A320 or 757's, I notice these aircraft climb fast, cruise high and sometimes descend up to around 4000 fpm at times, they seem to be getting up to the higher altitudes even on short hauls.

 

Edit: This is a copy from that website on that KLM 737-700:

 

 

• Altitude: 25750 ft (7849 m)

• V/S: 3328 fpm

AFAIK, the airlines would rather take an underpowered NG over an overpowered 757. With the NG, they can carry nearly the same amount of passengers but at lower fuel costs due to the lower throughput of the CFMs used on the 737.

 

All the airlines are looking for are aircraft that get from Point A to Point B with the lowest costs possible...

 

(The -900ER is quite close to the 757-200 in seating capacity.)

 

Keep these comments coming. I'm surprised an airliner with this kind of performance is the alternative for airlines. Can someone explain how throttled up engines taking much longer to get to cruise altitudes is more fuel efficient? You would think an airliner that can efficiently get to cruise without struggle (like the 757) would save fuel. Takeoff and climb burns the most fuel.

It's funny I remember seeing a show on the History Channel where they did a piece on KLGA in talking about the MD-80 being a less efficient bird to get off the runway and special care was needed when dealing with that bird. Now we have the much newer -900 more of a problem. You'd think things would progress not degress.

Dillon, do you use http://www.flightradar24.com

 

Awesome site. After watching a couple of 800/900 flights I'm convinced iFly got it right in the performance department. Thanks...