PMDG 737-700 Landing question

[NZAA 18]

I’ve been a flyby wire A320 fan for a very long time and I still love this aircraft. I’ve purchased the PMDG 737 for some variety and what an amazing aircraft this is.

I’m still getting my head around some of the differences. 

my flights to date have been using and ILS approach, I’m disengaging autopilot when I’m close and have good visual. My question is how or what should I be doing to reduce speed before touchdown? Do I need to disengage autothrottle or what is the process exactly

[sd_flyer 6,042]

I don't know the proper way to do it, but I at 1000 ft AGL I disengage AT first, then autopilot, and after that continue hand flying approach!

[Bobsk8 12,730]

Just now, NZAA said:

I’ve been a flyby wire A320 fan for a very long time and I still love this aircraft. I’ve purchased the PMDG 737 for some variety and what an amazing aircraft this is.

I’m still getting my head around some of the differences. 

my flights to date have been using and ILS approach, I’m disengaging autopilot when I’m close and have good visual. My question is how or what should I be doing to reduce speed before touchdown? Do I need to disengage autothrottle or what is the process exactly

I flew a 767_400 ER Full motion sim some years ago with a Delta Check Captain coaching me . He told me to leave the autothrottle on, on the approach set to Vref, as I would be too busy looking for traffic, etc, to be staring at the airspeed indicator. When about to touch down, turn it off. 

[ArkRoyal 30]

Assuming a coupled ILS approach, at 1000' you should be 'stable': landing flap (30 under normal circumstances), gear-down, speed (if not at, then within 10 kts) of Vref +5 (let's not complicate matters about Vapp) and thrust as per the autothrust (55% N1 is a good ballpark setting), landing checks complete.

The aircraft will have trimmed itself out and on disengaging autopilot and autothrust, (on a still day) it will almost fly itself with just minimal control input required.

[sidfadc 1,344]

 

 

[Stearmandriver 2,296]

It will vary by operator as to whether you're allowed to land with the autothrottles on.  They will reduce to idle in the flare for you if you leave them on, but in the real world there are pros and cons to this, hence the procedural differences among operators.  At my airline, our rule is to disconnect the autothrottles when we disconnect the autopilot; I'd say somewhere on base is the average time people do that, but it's up to you. 

I'm pretty sure PMDG modeled correct autothrottle behavior in the flare, so you can give it a try both ways in the sim and see what you like. 

[ahsmatt7 1,199]

We disconnect the auto throttles unless its an autoland. 
 

disconnect both the autopilot and the auto throttle and just fly the plane. 
 

At 50 ft, transition your view to the far end of the runway, at 30ft, pull power to idle and start your round out. As

long as the countdown from 30-20-10 takes about one second per number, youre doing great.

[Tom Wright 438]

I think in all variants of the 737 the standard procedure regarding autothrottle use is that it is disengaged whenever the autopilot is disengaged, unlike the 777 or the Airbus where it is the norm to fly with autothrottle on even when hand flying.

[VBHB 298]

I heard flap 40 is fun.

[Stearmandriver 2,296]

I believe at least American Airlines is authorized to land manually with the autothrottles engaged and it is the norm, or at least so I remember being told by one of their pilots who was in my jumpseat.  Would be interesting to confirm. 

Edited May 19, 2022 by Stearmandriver

[Chock 17,769]

On a 737 NG, the autothrottle takes data from the radar altimeter and closes the throttle automatically at a suitable altitude (27 feet AGL), which is why it is fairly important to have the Vref speed set up correctly for the weight. As the aeroplane flares, the speed bleeds off and theoretically you come in and touchdown at the correct speed, but it is still the job of the co-pilot (i.e. the pilot monitoring) to observe the speeds and stuff to make sure everything is cool. However, various types of autoland categories require certain parameters to be met (runway visual range, MDA, that sort of stuff) and the crew have to be qualified and current on the approach/autoland type. Since this is not always the case, it's fairly common to do an automatic ILS approach initially, then disengage everything and finish the landing manually, and to do that, basically you want to be switching everything automatic off as you come over the runway threshold, closing the throttle manually and using the flare to bleed off speed so you touchdown smoothly.

At light weights, a 737 will float quite a bit and since it will be in ground effect at low altitude (the air being forced down under the wing bounces off the ground and provides a cushion which the aeroplane rides on). Surprisingly, in these circumstances, a 737 NG can be at speeds as low as around 100 knots and still not completely quit flying owing to that air cushion effect, so you need to be aware of this. The 737 is known to be a bit 'floaty' compared to the A320 as a result of it not having as long an undercarriage as is found on the Airbus, and if you are used to flying an A320, it is as well to be aware of how this makes the 737's fairly different to the A320 in terms of landing despite the fact that they are basically rival aeroplane types.

A good example of a real world accident where all this stuff came into play, is the heavy crash-landing of Turkish Airlines Flight 1951 at Schiphol in 2009. Part of the problem was the F/O's inexperience in arming the autoland system correctly (there are a number of ways to do this, and how you do it and in what order you press the MCP buttons depends on whether it will be a single channel or dual channel automatic approach), but there was also a fault with the altimeter system and in addition to this, the pilot monitoring wasn't doing his job properly either owing to cockpit distractions.

Things were not helped by the fact that ATC had the crew intercept the glideslope from above, which is not really what you are supposed to do, and in pulling the throttles back to try to get down onto the glideslope, the throttles automatically went into retard mode owing to the radar altimeter's erroneous information. The pilots did open the throttles up again, but if you move the throttles briefly to do this instead of holding them there, they will not stay in that position and will revert back to their autothrottle setting (in this case, idle). Because the crew were doing an autoland, they assumed all the automatic systems would function as they supposed, which they did not. This would not have been a problem if the crew had taken corrective actions, but since the aeroplane's systems were incorrectly indicating that it was at low altitude and about to touch down, the autothrottle closed when the aeroplane was still a couple of thousand feet above the ground. The crew were somewhat distracted by the fact that there was a third crewmember in the cockpit involved in training, so the pilot who was supposed to be watching the airspeeds and such, did not monitor the instruments properly, which would have alerted him to there being something wrong, and in any case with a not properly stabilised approach, this should have been a situation where he advised going around.

With the autothrottle closed, the aeroplane began slowing down and dropping below the glideslope, the aeroplane actually dropped to a speed of less than 90 knots and at about 500 feet the stick shaker went off to indicate an imminent stall. At this point the pilots rammed the throttles wide open and the engines did on this occasion begin to spool up, but by that time the thing was too low and too slow to stay airborne and it smashed into the ground heavily in a tail down attitude at about 95 knots, breaking into three sections as it slid along in a ploughed field a few hundred yards short of the runway, resulting in nine fatalities (including all the cockpit crew) with most of the rest of the passengers being injured, several of them pretty seriously.

If you want a good book on flying the 737, and indeed a good website too. Then have a look here.

Edited May 19, 2022 by Chock

[ArkRoyal 30]

FCTM:

'Autothrottle use is recommended during takeoff and climb in either automatic or manual flight. During all other phases of flight, autothrottle use is recommended only when the autopilot is engaged in CMD.

During engine out operations, Boeing recommends disconnecting the autothrottle and keeping the throttle of the inoperative engine in the CLOSE position. This helps the crew recognize the inoperative engine and reduces the number of unanticipated thrust changes.
Note: The autothrottle logic on some airplanes allows the autothrottle to be physically connected during engine out operations.'

The document also states ad nauseam to make the point:

'The autothrottle should be disconnected when the autopilot is disengaged.'

 

[SierraHotel 982]

12 hours ago, NZAA said:

I’ve been a flyby wire A320 fan for a very long time and I still love this aircraft. I’ve purchased the PMDG 737 for some variety and what an amazing aircraft this is.

I’m still getting my head around some of the differences. 

my flights to date have been using and ILS approach, I’m disengaging autopilot when I’m close and have good visual. My question is how or what should I be doing to reduce speed before touchdown? Do I need to disengage autothrottle or what is the process exactly

This is Emanuel, he is a current 737 pilot and was on the PMDG team that built the 700, his channel is the place to go for in depth tutorials on flying this beautiful bird.

https://www.youtube.com/channel/UCJku5jC23Y0MkmPqU7CZhog

This also might come in handy:-

Boeing 737-700/800
Flight Crew Operation Manual

http://navfly.ru/wp-content/uploads/2017/10/FCOM-003-all-online.pdf

Edited May 19, 2022 by SierraHotel

[Ilari Kousa 116]

19 minutes ago, ArkRoyal said:

FCTM:

'Autothrottle use is recommended during takeoff and climb in either automatic or manual flight. During all other phases of flight, autothrottle use is recommended only when the autopilot is engaged in CMD.

During engine out operations, Boeing recommends disconnecting the autothrottle and keeping the throttle of the inoperative engine in the CLOSE position. This helps the crew recognize the inoperative engine and reduces the number of unanticipated thrust changes.
Note: The autothrottle logic on some airplanes allows the autothrottle to be physically connected during engine out operations.'

The document also states ad nauseam to make the point:

'The autothrottle should be disconnected when the autopilot is disengaged.'

 

This has changed recently to harmonise it with the rest of the fleet. Boeing now permits landing with the A/T in, but many operators will have you disconnect anyway. Some operators, such as Lufthansa, will have you do this even in the Airbus. Others, such as BA, *require* you to leave the autothrust in unless it has failed. Others don't care.

[Christopher Low 5,353]

14 hours ago, NZAA said:

I’ve been a flyby wire A320 fan for a very long time and I still love this aircraft. I’ve purchased the PMDG 737 for some variety and what an amazing aircraft this is.

I’m still getting my head around some of the differences. 

my flights to date have been using and ILS approach, I’m disengaging autopilot when I’m close and have good visual. My question is how or what should I be doing to reduce speed before touchdown? Do I need to disengage autothrottle or what is the process exactly

As far as I am aware, the aircraft should be stabilised on approach when the autopilot is disengaged. That means that the speed should already be at Vref, assuming that you have been using the autothrottle correctly.

Edited May 19, 2022 by Christopher Low