Fastest way to delete only the speed restriction on the fmc?

[Boeing or not going 578]

What is the fastest way to remove only a speed restriction on a sid/star? Use the Delete key to wipe the line. Add the altitude restriction back? Can be time consuming with 3 or 4 legs to change. Hoping to find the fastest way to do this for saving times sake! Thanks - David Lee

[scandinavian13 5,192]

1 hour ago, Boeing or not going said:

What is the fastest way to remove only a speed restriction on a sid/star? Use the Delete key to wipe the line. Add the altitude restriction back? Can be time consuming with 3 or 4 legs to change. Hoping to find the fastest way to do this for saving times sake! Thanks - David Lee

Use SPD INTV, or do as you described.

[Boeing or not going 578]

5 minutes ago, scandinavian13 said:

Use SPD INTV, or do as you described.

To keep the vnav profile I will do as I described I thought there could be a faster way.  - David Lee

[berts 97]

2 hours ago, scandinavian13 said:

Use SPD INTV, or do as you described.

Normally the speed and altitude restriction in the FMC will go together, so for example when ATC says cancel the speed restriction below 10,000ft the easiest way is to simply press the DEL key, line select it over the 250/10000 speed/altitude restriction (then in the real world confirm the action with your P2!) before pressing the EXEC button and verifying the action is executed correctly on your PFD. 

If you need to delete only a speed restriction on a particualr LEG, but not the altitude then, as Kyle says, the easiest way is to use the SPD switch and SPD Intervene.  However, if you need to delete both (i.e to prevent one or more intermediate speed and altitude captures during a climb to cruising altitude) then you can delete them in turn on the LEGS page by simply pressing the Altitude Selector knob for each one whilst monitoring what happens to each restriction on the LEGS page. 

David, no matter how many actions you need to take which will affect the flight path of your aircraft they should always be carried out slowly and deliberately.   This is about workload distribution and In the case of a multi-crew aircaft the other crew member will usually be flying the aircraft on autopilot and able to monitor your actions.  You should never attempt to do anything in an aircraft faster or quicker, because more haste usually means less speed and this could lead to a potential accident if you are not careful!

Bertie G

 

 

[markadeane 272]

3 hours ago, Boeing or not going said:

To keep the vnav profile I will do as I described I thought there could be a faster way.  - David Lee

If I recall correctly SPD INTV doesn't remove the altitude constraints, just the speed. Of course if you remove a speed constraint on - say - a SID, the aircraft will pitch over to accelerate and you might then have trouble making any at-or-above altitude constraints anyway. Conversely if you're removing speed constraints on a STAR, make sure that you don't end up arriving at the approach with bags of excess energy or you'll have a hard time configuring for landing!

Side note from a procedure designer standpoint: If there's a speed on a SID or STAR it will be there for a reason. Some of them are ATC related and can be waived, but often they're design-related, sometimes to assist with achieving a high climb gradient on a SID, other times to ensure that an aircraft can successfully negotiate a large turn angle or a sequence of turns (e.g. RNAV approach 'T-Bar' with 4nm legs). Exceeding a speed limit may impact on the 'flyability' of the procedure.

Edited May 2, 2018 by markadeane

[thibodba57 462]

3 hours ago, markadeane said:

Of course if you remove a speed constraint on - say - a SID, the aircraft will pitch over to accelerate and you might then have trouble making any at-or-above altitude constraints anyway. 

Should not be an issue.  SPD INTV will still honor altitude constraints and try to maintain path.  So if you are descending at 290 KIAS. And open the window and dial in 310, the aircraft should just add power and adjust it's pitch to try to stay on PTH. If it goes off PTH it will level at the altitude constraint add a bunch more power to maintain the commanded speed.

[godimaginedme 25]

It depends on the segment of flight. If you are descending on an arrival with speed and altitude restrictions, flying in LNAV and VNAV together with the speed window 'closed' will cause the plane to project and plan for any upcoming restrictions. If ATC says 'delete the speeds on the arrival' one way to ignore the speeds is to (depending on aircraft) open the speed window/use spd inv. to select the speed you want. Assuming you are still in LNAV and VNAV, the descent mode will change from VNAV PTH to VNAV SPD (assuming you are using a legacy version of the FMC). Altitude restrictions will still be maintained, however you must make the airplane descend after each altitude constraint is met (in VNAV SPD). The altitude mode will change to VNAV ALT. The plane will never leave a VNAV ALT condition unless you are on a segment of the actual instrument approach past the IAF, or you force the plane to continue descent. This is because the speed entered in the speed window on the MCP is variable and the plane can not project what the correct descent path should be. The best way to mitigate this poriental cluster ... is to delete the speed restriction as you described in your initial post, but re-enter the altitude restriction as you suggested. It may seem like it is time consuming, but it'll save you a headache down the road. Long story short, SPD INV is useful for short periods, but not an entire segment.

Edited May 3, 2018 by godimaginedme

[markadeane 272]

2 hours ago, thibodba57 said:

Should not be an issue.  SPD INTV will still honor altitude constraints and try to maintain path.  So if you are descending at 290 KIAS. And open the window and dial in 310, the aircraft should just add power and adjust it's pitch to try to stay on PTH. If it goes off PTH it will level at the altitude constraint add a bunch more power to maintain the commanded speed.

Thanks Brian, you're quite right of course!

[iwebber 207]

8 hours ago, markadeane said:

Of course if you remove a speed constraint on - say - a SID, the aircraft will pitch over to accelerate and you might then have trouble making any at-or-above altitude constraints anyway.

 

5 hours ago, thibodba57 said:

Should not be an issue.  SPD INTV will still honor altitude constraints and try to maintain path.  So if you are descending at 290 KIAS. And open the window and dial in 310, the aircraft should just add power and adjust it's pitch to try to stay on PTH. If it goes off PTH it will level at the altitude constraint add a bunch more power to maintain the commanded speed. 

He's dead right, on a SID (or in a climb segment), if you increase speed it will fly the speed (not the path) so you may find you get a "UNABLE NEXT ALT" FMC message and you won't make the alt restriction (assuming the restriction is an at or above XXX).

We often use speed intervene to make alt restrictions by keeping the speed back to get a better angle of climb.

On a STAR (or descent segment) you are, indeed, correct, it will fly the path, although if you set too low a speed it will find it can't make the path and eventually dump you out of VNAV and give you UNABLE NEXT ALT (assuming an at or below constraint).

HTH

Ian Webber

 

[costamesa 88]

I am confused now. I thought typing "/" and then whatever speed you want (like "/XXX"), to stractpad would delete the "restriction"?

[G-CIVA 62]

Use a lower level of automation to keep brain ahead of airplane.

Sort out the 'syntax' in the 'box' once you have the aircraft headed in the correct direction laterally, vertically with the correct velocity/energy (if time permits).

VNAV is a 'strategic' tool that was primarily designed to get aircraft across long distances through multiple flight levels in conjunction with LNAV with remarkable accuracy; granted it now has additional uses with appropriately equipped & certified aircraft (& crews) performing various types of coded departures & arrivals & approaches but the statement above still stands, i.e. where appropriate select a lower level of automation to get the aircraft headed where you want it to go - or ATC WANT YOU TO GO - then re engage all the bells & whistles you want to should the situation allow or it be appropriate.

Edited May 3, 2018 by G-CIVA

[Boeing or not going 578]

18 hours ago, berts said:

David, no matter how many actions you need to take which will affect the flight path of your aircraft they should always be carried out slowly and deliberately.   This is about workload distribution and In the case of a multi-crew aircaft the other crew member will usually be flying the aircraft on autopilot and able to monitor your actions.  You should never attempt to do anything in an aircraft faster or quicker, because more haste usually means less speed and this could lead to a potential accident if you are not careful!

Bertie G

 

 

Bertie, I am with you here, but flight simulation is not real life. I fly with the real atc talking to the flight on liveatc.net feeds, or I will fly on Vatsim. PMDG is not shared cockpit so I am all alone doing the job of 2 people and want to make some basic tasks quicker. - David Lee

[scandinavian13 5,192]

29 minutes ago, Boeing or not going said:

Bertie, I am with you here, but flight simulation is not real life. I fly with the real atc talking to the flight on liveatc.net feeds, or I will fly on Vatsim. PMDG is not shared cockpit so I am all alone doing the job of 2 people and want to make some basic tasks quicker. - David Lee

Deleting a speed restriction isn't something ATC needs quickly. Slow down. Do it correctly in the time it takes.

[skelsey 765]

The only other thing I would add is that "no ATC speed restriction" is not equal to "fly 350 KIAS".

If ATC lift a speed restriction, you do not automatically have to immediately wind up the engines and get the ASI pegged to the barber pole. Indeed, in many situations it would be inappropriate to do so, especially in the situations Mark and Ian allude to above; arrival and departure procedures rely upon accurate lateral tracking not only for noise preferential routes, but potentially also for terrain or airspace constraints and lateral tracking performance is directly related to airspeed. Likewise climb rate/gradient may be an issue in some cases, as will energy management on descent.

Sure, if you're above MSA and clear of any tight turns then you may well wish to go for it. Or not -- by the time you've done that, how much time are you going to save by the time you've wound the speed up and faffed around with the CDU before you're above FL100 anyway?

If ATC want you to fly a given speed then they'll give it to you: if all they're doing is saying "no ATC speed restriction", you are entirely within your rights to say "thank you very much" and do absolutely nothing differently if you don't feel inclined.

[scandinavian13 5,192]

2 hours ago, skelsey said:

If ATC want you to fly a given speed then they'll give it to you: if all they're doing is saying "no ATC speed restriction", you are entirely within your rights to say "thank you very much" and do absolutely nothing differently if you don't feel inclined.

Exactly. Well said.

As far as the controller toolbox goes, speed is usually the last tool to get used: vector, altitude, and then speed. Speed is usually the last tool used (particularly in the terminal environment) because it often takes the longest to take effect, in terms of spacing things out. Moreover, it's usually the most difficult to manage if you have busy airspace, unless you're telling everyone "200 to XXFIX," but those cases simply cause the delay to cascade back. If you're efficiently vectoring, you can make those tactical adjustments on the fly, provided you have the airspace real estate to make that happen (not always an option, which is why you'll hear the earlier "[speed] to [fix]" instruction).

Execute things as quickly as possible, but unless they say "no delay" or "immediate" (or similar), there's no need to be on high alert about it.