Boeing 737 descent without VNAV
Joined: Dec 2005
Posts: 21
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From: Frisco, Texas USA
I was taught this when I flew the L1011, it worked on the B757 and now the B737. Caution: this is technique only.
Take your altitude loss required, ex. 30,000 - 10,000 = 20,000.
Divide by 1000, ex. 20,000/1,000 = 20.
Multiply by 3 = 60. Now 60 miles is the distance needed to descend 20,000'. In calm winds. Start your descent at least 60 nm prior to your crossing restriction.
Now, I'm sure you're asking, "but what speed?" It worked for me for Mach .84 to Mach .82 to Mach .78 with a transitions from 340, 320, 300 kts. because...
... you should plan to descend at a rate 5 times your ground speed. In calm winds a B737 will by going around 450-500 kts. 5 x 450 = 2250 fpm. This is roughly what a B737 will descend at.
So, it takes 4-5 nm to decelerate from 300 to 250 kts without using speed brakes. It takes about 4nm to decelerate from 250 to 210kts Try to plan NOT using speed brakes.
So (again) add this 5 nm to the 60 planned above, and you should theoretically be at your altitude 5 nm prior to the requirement. If you have to slow, you can slow down after you level off without speed brakes. With the desired altitude set in your MCP, use your altitude trend reference symbol, i.e. the "green banana," on our ND to monitor your progress.
Now, if you're trying to slow down while descending, know that the A/P is not very aggressive. Whether you're in LVL CHG or SPD INV in VNAV, the A/P will aim to descend at 500 fpm, which will allow it to descend and decelerate, theoretically.
Here's another gem. If you're in VNAV or with GS CAP on a 3º glide path/slope, you can maintain 250 kts until 12 nm out, calm winds considered, then you can throw your gear out, slow down and configure on speed to be stable by 1000' agl. The 1st time you try this, use the speed brake with the gear to slow and configure. This should give you confidence.
Take your altitude loss required, ex. 30,000 - 10,000 = 20,000.
Divide by 1000, ex. 20,000/1,000 = 20.
Multiply by 3 = 60. Now 60 miles is the distance needed to descend 20,000'. In calm winds. Start your descent at least 60 nm prior to your crossing restriction.
Now, I'm sure you're asking, "but what speed?" It worked for me for Mach .84 to Mach .82 to Mach .78 with a transitions from 340, 320, 300 kts. because...
... you should plan to descend at a rate 5 times your ground speed. In calm winds a B737 will by going around 450-500 kts. 5 x 450 = 2250 fpm. This is roughly what a B737 will descend at.
So, it takes 4-5 nm to decelerate from 300 to 250 kts without using speed brakes. It takes about 4nm to decelerate from 250 to 210kts Try to plan NOT using speed brakes.
So (again) add this 5 nm to the 60 planned above, and you should theoretically be at your altitude 5 nm prior to the requirement. If you have to slow, you can slow down after you level off without speed brakes. With the desired altitude set in your MCP, use your altitude trend reference symbol, i.e. the "green banana," on our ND to monitor your progress.
Now, if you're trying to slow down while descending, know that the A/P is not very aggressive. Whether you're in LVL CHG or SPD INV in VNAV, the A/P will aim to descend at 500 fpm, which will allow it to descend and decelerate, theoretically.
Here's another gem. If you're in VNAV or with GS CAP on a 3º glide path/slope, you can maintain 250 kts until 12 nm out, calm winds considered, then you can throw your gear out, slow down and configure on speed to be stable by 1000' agl. The 1st time you try this, use the speed brake with the gear to slow and configure. This should give you confidence.
Joined: Jun 2013
Posts: 349
Likes: 20
From: egll
Here's another gem. If you're in VNAV or with GS CAP on a 3º glide path/slope, you can maintain 250 kts until 12 nm out, calm winds considered, then you can throw your gear out, slow down and configure on speed to be stable by 1000' agl. The 1st time you try this, use the speed brake with the gear to slow and configure. This should give you confidence.
(speedbrake with the gear is expressly forbidden too, an OFDM trigger).
Joined: Feb 2003
Posts: 543
Likes: 337
From: Blue sky
Boeing does not talk about SOPs, it explains in the FCTM and uses words like "normal" and "not recommended". When it comes to landing gear it uses words as "passenger comfort" and "gear door life". It explains how to, or to avoid, use of flaps, gear and speedbrake as a combo. On the other side, the problem with these "demo's" is that people tend to use it as a standard because "they can". This is a training issue: you can show/demo an ability, that doesn't make it a standard practice. But against SOPs?
Simple case of RTFM.
Last edited by BraceBrace; 22nd February 2025 at 08:24.
Joined: Dec 2023
Aviation Qualifications: ATPL
Posts: 207
Likes: 157
From: UK
There is NO need for anyone to use the speedbrake with the landing gear down in normal operations.
Alone, the landing gear will slow the aircraft down or help increase the descent rate with the drag if you keep the speed up.
Alone, the landing gear will slow the aircraft down or help increase the descent rate with the drag if you keep the speed up.
Joined: Dec 2020
Aviation Qualifications: ATPL
Posts: 573
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From: https://youtube.com/watch?v=P8pihdksUHk&si=t_GX3ubmBvZ2CDgB
.
We didn't have FMS in my day.
As a rule of thumb, from light, jets throught to heavies, we used this. 3 x the altitude. 3 degree decent angle. So, if you were at 30,000ft x 3 = 90 miles plus 10, for TOD. If you were going down at less than less than 3 degs, and unable too reduce power (pressurization), increase speed, more drag.
Higher the A/C weight, the more distance required, for a given speed. (Same reason a glider carries water ballast). Keep a check, if you are on profile, during descent.
We didn't use calculators, as they weren't around then either. K.I.S.
As for the use of spoilers in the air. Dont use them, in normal procedures. Observe an a/c landing. As soon as spoilers are deployed, watch the horizontal stabliser. The movement, caused by disturbed airflow from deployed spoilers, is disturbing to watch. Imagine the movement at twice the A/S. With prolonged use in the air
If you bend a piece of metal often and long enough, it will fail.
As a rule of thumb, from light, jets throught to heavies, we used this. 3 x the altitude. 3 degree decent angle. So, if you were at 30,000ft x 3 = 90 miles plus 10, for TOD. If you were going down at less than less than 3 degs, and unable too reduce power (pressurization), increase speed, more drag.
Higher the A/C weight, the more distance required, for a given speed. (Same reason a glider carries water ballast). Keep a check, if you are on profile, during descent.
We didn't use calculators, as they weren't around then either. K.I.S.
As for the use of spoilers in the air. Dont use them, in normal procedures. Observe an a/c landing. As soon as spoilers are deployed, watch the horizontal stabliser. The movement, caused by disturbed airflow from deployed spoilers, is disturbing to watch. Imagine the movement at twice the A/S. With prolonged use in the air
If you bend a piece of metal often and long enough, it will fail.
Last edited by RichardJones; 22nd February 2025 at 10:55.
Joined: Jun 2013
Posts: 349
Likes: 20
From: egll
Company SOP, what company has these kinds of SOPs? There is a standard practice, that does not mean it is an SOP?
Boeing does not talk about SOPs, it explains in the FCTM and uses words like "normal" and "not recommended". When it comes to landing gear it uses words as "passenger comfort" and "gear door life". It explains how to, or to avoid, use of flaps, gear and speedbrake as a combo. On the other side, the problem with these "demo's" is that people tend to use it as a standard because "they can". This is a training issue: you can show/demo an ability, that doesn't make it a standard practice. But against SOPs?
Simple case of RTFM.
Boeing does not talk about SOPs, it explains in the FCTM and uses words like "normal" and "not recommended". When it comes to landing gear it uses words as "passenger comfort" and "gear door life". It explains how to, or to avoid, use of flaps, gear and speedbrake as a combo. On the other side, the problem with these "demo's" is that people tend to use it as a standard because "they can". This is a training issue: you can show/demo an ability, that doesn't make it a standard practice. But against SOPs?
Simple case of RTFM.
RTFM, indeed.
Gender Faculty Specialist
Joined: Mar 2002
Aviation Qualifications: ATPL
Posts: 2,325
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From: In your head.
I would love to be able to fly like this, however 99.9% of captains would scream at me and any who allowed me to would end up in an office meeting explaining why they let me. Absolutely against all company SOP
(speedbrake with the gear is expressly forbidden too, an OFDM trigger).
(speedbrake with the gear is expressly forbidden too, an OFDM trigger).
Joined: Feb 2003
Posts: 543
Likes: 337
From: Blue sky
For all I know, you can do an emergency descent with the landing gear down... you're not allowed to use speedbrakes? Don't read that anywhere.
Last edited by BraceBrace; 22nd February 2025 at 22:27.
Joined: Jan 2019
Posts: 337
Likes: 82
From: Australia
As for the use of spoilers in the air. Dont use them, in normal procedures. Observe an a/c landing. As soon as spoilers are deployed, watch the horizontal stabliser. The movement, caused by disturbed airflow from deployed spoilers, is disturbing to watch. Imagine the movement at twice the A/S. With prolonged use in the air
If you bend a piece of metal often and long enough, it will fail.
If you bend a piece of metal often and long enough, it will fail.
Joined: Dec 2020
Aviation Qualifications: ATPL
Posts: 573
Likes: 296
From: https://youtube.com/watch?v=P8pihdksUHk&si=t_GX3ubmBvZ2CDgB
There was a.crew change at Nairobi. The incoming Captain, mentioned to the out going crew, they couldn't quite get the nose up trim on landing. They said they would take it, see what happens.
If there are any doubts, periodically, on the ground, it is worth winding the trim full forward, and do an external check of the stabliser position against the fuselage markings for assimectrics. Do the same, full nose up.
Some pilots used outboard spoilers, only in the air. I wasn't that keen, Putting the gear down was very effective.
Last edited by RichardJones; 23rd February 2025 at 02:05.
Gender Faculty Specialist
Joined: Mar 2002
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From: In your head.
As will selecting gear and flap repeatedly at the limitng speeds. Higher stresses, higher vibrations, higher air loads, will all lead to premature metal fatigue.
Joined: Feb 2025
Posts: 4
Likes: 0
From: Europe
But in normal and expected conditions many SOPs restrict using some techniques (for example ALTN MCP technique, flaps policy, speed brakes policy etc.).
One of my operators doesn’t allow to use SPD BRKs with Flaps more than 15 (FDR trigger).
What about descend rules? To my mind it’s PF responsible (of course ur colleagues should understand your strategy).
There are many techniques, for example:
1.PROG distance*3-1000 ft
2.(PROG distance*3)- 10 nm
3.Cross check at typical ALT vs total distance remaining:
-10.000 FT= 37 nm (FPPM value for 0.78/280/250 descend with allowance for deceleration to F15 configuration at distance approximately 7 nm from touchdown)
-5.000 FT= 22 nm (same as above)
4. Set WPT/ALT (on DES page) probable shortcut waypoint (IF/FAF) or just RWY/elevation, observe VS required, and set VS= VS required+300…500 fpm)
5. Just restrict IAF,IF, FAF to “AT” and set at IF/FAF Vapp instead of 180B, 160B (for example) - ALWAYS COMPLY WITH STAR/APP/ATC RESTRICTIONS AND DO NOT MODIFY LEGS WITHOUT ATC PERMISSION. Set on DESC FORECAST page tailwind at base and final legs (it can help you by extending DECEL segment).
In all cases comply with your SOP, ATC,AIRSPACE and make sure your colleagues understand your intentions.
Joined: Dec 2003
Posts: 2,347
Likes: 838
From: Tring, UK
I would love to be able to fly like this, however 99.9% of captains would scream at me and any who allowed me to would end up in an office meeting explaining why they let me. Absolutely against all company SOP
(speedbrake with the gear is expressly forbidden too, an OFDM trigger).
(speedbrake with the gear is expressly forbidden too, an OFDM trigger).
What do you do when you have the gear down coming into land and ATC say "reduce *now* to minimum approach speed, slower traffic ahead”? Or it looks like you need to lose a bit of energy to be stable at 1000R?
I used to fly the 737 and there was nothing then in the manuals about gear + speedbrake. On the 777 the speedbrakes are another primary flying control and are used on almost every approach; you can land with them fully deployed if you really want to.
Joined: Feb 2003
Posts: 543
Likes: 337
From: Blue sky
Speedbrakes beyond Flaps 15 has nothing to do with landing gear limitations. There is a limitation you cannot go beyond flight detent in flight, there is a limitation you cannot use speedbrakes below 1000ft _RA_.
Big takeaway that might one day save your life: FDM TRIGGERS ARE NOT LIMITATIONS. Otherwise you can't even go-around. Triggering an FDM might one day avoid you get into deep ####. Triggering limitations means you are already are in deep #### as Boeing does not guarantee anything.
Last edited by BraceBrace; 23rd February 2025 at 14:29.
