Deleting hard heights
Joined: Jun 2000
Posts: 4,507
Likes: 4
From: last time I looked I was still here.
IMHO this is not an SOP fist fight.
Delete them as you please, just don't bust the level off.
IMHO it is more an airmanship and awareness tool issue. At times like this I always ask a relevant question, depending on the issue. In this case the FMC has a hard altitude in its data base for the SID. ATC clear you for the SID. You enter the altitude in MCP. Now, for the briefing you have a displayed confirmation between the FMC and MCP about the clearance. To delete the altitude in the FMC requires extra steps, effort, crew confirmation, (I'm sure you wouldn't do it on your own, would you).
The question is; how have you improved the situation by deleting the FMC Altitude? You haven't; but you've spent conscious effort & thought doing it. Why? There are some operators that depart in VNAV, or will use that mode after flaps up. VNAV will capture the FMC ALT. By removing it you are relying solely on MCP. We do so many things with belt & braces. Removes the braces, and if the belt is too lose, your trousers fall down.
I flew with a couple of operators who did have an SOP. If the SID cap was not associated with a WPT then it was not in the FMC data base. It was a requirement to enter the cap at a suitable WPT in the FMC, for the reasons stated above. IMHO seemed like a good idea.
Delete them as you please, just don't bust the level off.
IMHO it is more an airmanship and awareness tool issue. At times like this I always ask a relevant question, depending on the issue. In this case the FMC has a hard altitude in its data base for the SID. ATC clear you for the SID. You enter the altitude in MCP. Now, for the briefing you have a displayed confirmation between the FMC and MCP about the clearance. To delete the altitude in the FMC requires extra steps, effort, crew confirmation, (I'm sure you wouldn't do it on your own, would you).
The question is; how have you improved the situation by deleting the FMC Altitude? You haven't; but you've spent conscious effort & thought doing it. Why? There are some operators that depart in VNAV, or will use that mode after flaps up. VNAV will capture the FMC ALT. By removing it you are relying solely on MCP. We do so many things with belt & braces. Removes the braces, and if the belt is too lose, your trousers fall down.
I flew with a couple of operators who did have an SOP. If the SID cap was not associated with a WPT then it was not in the FMC data base. It was a requirement to enter the cap at a suitable WPT in the FMC, for the reasons stated above. IMHO seemed like a good idea.
Joined: Sep 2016
Posts: 936
Likes: 67
From: USA
Yeah, I see no advantage and every possible disadvantage for getting cleared to 4000 and deleting the 4000 from the FMS. This makes no sense, and I don't see why anybody would want to do that.
Tonker, are you sure you didn't mean to ask about, for example, getting cleared to 5000 and deleting the 4000?
Tonker, are you sure you didn't mean to ask about, for example, getting cleared to 5000 and deleting the 4000?
Joined: Jan 2006
Aviation Qualifications: CPL
Posts: 1,409
Likes: 46
From: Between a rock and a hard place
My reasoning; If you keep/insert hard altitudes out of London then you better do it at all other ports as well. I know some operators do it. My current airline has no procedure/culture doing so. We're two pilots that go through the routing and stop altitude during the briefing. Has worked well so far and doesn't seem to cause any altitude deviations. Lastly the the FMC will only stop you if climbing in VNAV which many aren't doing approaching a low level off.
Joined: Jan 2006
Aviation Qualifications: CPL
Posts: 1,409
Likes: 46
From: Between a rock and a hard place
I might just be slow, but I like to keep it clean and control my altitude in one place (that would be the MCP). What would happen if I am slowly climbing in V/S to 5000 ft enroute to a fix with a 4000 ft hard altitude. I forget to follow up pressing ALT INTV once, twice, three times.... Then cleared up high to FL170 and press VNAV? It will probably show an error message and disconnect VNAV? Just speculating through the grapevine.
Joined: Apr 2003
Aviation Qualifications: ATPL
Posts: 3,649
Likes: 491
From: Europe
Direct To's REQUIRE an alteraton in the MCDU, a SPD change doesn't smart arse. That is what Airbus say the FCU is for.
Not surprisingly you are missing my point completely. As PF, I use the FCU. So why is the F/O clearing speeds from the MCDU without being asked to do so and without confirmation?
Sorry I forgot, F/O's run the Flight Deck these days.
Not surprisingly you are missing my point completely. As PF, I use the FCU. So why is the F/O clearing speeds from the MCDU without being asked to do so and without confirmation?
Sorry I forgot, F/O's run the Flight Deck these days.
I have worked for an airline where deleting hard heights on the SID was SOP. Currently I operate without any hard guidance regarding these heights other than the mention that some specific countries like you adhere to these heights on descent even when cleared direct to a further waypoint.
So in practice in descent I clear useless hard heights, for example the irrelevant 4000 at MAY on approach into LGW when I very well know that this will ruin my mandatory continuous descent under radar vectors, but keep those that really matter. On the SID I keep all hard heights in as it heightens situational awareness and that's also what the SOP's imply. This seems to work out fine, but if your SOP's differ then that's absolutely fine as well. All that matters is the pay check at the end of the month.
Last edited by PENKO; 29th April 2018 at 06:51.
Joined: Nov 1999
Aviation Qualifications: ATPL
Posts: 3,140
Likes: 740
From: UK
Both Airbus and Boeing have climb and descent modes that will ignore pre-programmed altitude constraints : Open climb/descent or Level change*. (I don’t know about other types).
So why bother to remove them ? As others have said; making unnecessary changes to programming carries a significant TEM risk, and while most of us are perfectly capable of changing constraints - be they speeds or altitudes - one day you might accidentally remove a rather vital waypoint instead.
There seems little point if the system can be ‘told’ to ignore altitude constraints. Better to use those extra few brain cells to concentrate on SA and busy traffic than go heads down. If a descent constraint is irrelevant on the day, and would schedule a descent too early or too late, then, OK, delete it, but otherwise probably safer to leave it alone.
After all, unintentionally levelling at a published SID/STAR constraint that ATC have cancelled is arguably safer than accidentally removing a complete waypoint?
*After years on the Airbus, am brand new to the Boeing, so please correct me if I am wrong.
So why bother to remove them ? As others have said; making unnecessary changes to programming carries a significant TEM risk, and while most of us are perfectly capable of changing constraints - be they speeds or altitudes - one day you might accidentally remove a rather vital waypoint instead.
There seems little point if the system can be ‘told’ to ignore altitude constraints. Better to use those extra few brain cells to concentrate on SA and busy traffic than go heads down. If a descent constraint is irrelevant on the day, and would schedule a descent too early or too late, then, OK, delete it, but otherwise probably safer to leave it alone.
After all, unintentionally levelling at a published SID/STAR constraint that ATC have cancelled is arguably safer than accidentally removing a complete waypoint?
*After years on the Airbus, am brand new to the Boeing, so please correct me if I am wrong.
Last edited by Uplinker; 1st May 2018 at 08:00. Reason: Readability
Joined: Dec 2003
Posts: 2,338
Likes: 821
From: Tring, UK
What’s the worst that can happen if you leave a hard restriction in on departure that gets in your way later on? The a/c attempting to level off earlier than you might like which is easily rectified, no harm done. Especially if you keep the FMAs in your scan.
If you delete something that was or became relevant, you are increasing the possibilities of a) a level bust, b) a TCAS event and/or c) an Airprox or worse.
Looking at those two alternatives from a risk PoV, which would you rather have...?
If you delete something that was or became relevant, you are increasing the possibilities of a) a level bust, b) a TCAS event and/or c) an Airprox or worse.
Looking at those two alternatives from a risk PoV, which would you rather have...?
