TCAS climb
Mach 3
Joined: Aug 1998
Posts: 624
Likes: 1
From: Stratosphere
Just another piece of information that might be helpful and lends credence to my former supposition that indeed max service alts are somewhat artificial.
(Interestingly, in the 737 series I fly, max service alt is FL370 but one may select up to FL420 on the pressurization panel. Seems to me then, from a systems point of view, the restriction limiting the airframe to this level is then either aerodynamic or somewhat artificial. My own experience suggests that certainly at light weights, the aircraft would be quite capable of climbing higher.)
I know that, certainly, on the Smiths FMC, there are relevant PERFORMANCE FACTORS (to the incident in question) which may be selected via the Maintenance Pages.
They are the Min ROC parameters in CLB, CRZ and ENG OUT and the MNVR MARGIN.
These are Management selectable options.
The ranges are:
MNVR MARGIN: 1.15 - 1.60
MIN ROC: 0-999 ft/min
Knowing what the company set these values at might reflect how they perceive the limit.
These values obviously don't change the certified service limit but they do govern how close one may approach the edge of the flight envelope in the various phases of flight.
And IMHO, if the FMC predicted MAX ALT at 58T with a CG location of 15% MAC is 368, it seems quite clear to me that at 50T, the aircraft is capable of going higher than 370 all other things being equal.
Won't help you out of a jam I suppose, but I believe it demonstrates the articial nature of the limitation in question.
That a breach of this limitation should even be considered akin to a breach where a TCAS RA was ignored is lamentable.
(Interestingly, in the 737 series I fly, max service alt is FL370 but one may select up to FL420 on the pressurization panel. Seems to me then, from a systems point of view, the restriction limiting the airframe to this level is then either aerodynamic or somewhat artificial. My own experience suggests that certainly at light weights, the aircraft would be quite capable of climbing higher.)
I know that, certainly, on the Smiths FMC, there are relevant PERFORMANCE FACTORS (to the incident in question) which may be selected via the Maintenance Pages.
They are the Min ROC parameters in CLB, CRZ and ENG OUT and the MNVR MARGIN.
These are Management selectable options.
The ranges are:
MNVR MARGIN: 1.15 - 1.60
MIN ROC: 0-999 ft/min
Knowing what the company set these values at might reflect how they perceive the limit.
These values obviously don't change the certified service limit but they do govern how close one may approach the edge of the flight envelope in the various phases of flight.
And IMHO, if the FMC predicted MAX ALT at 58T with a CG location of 15% MAC is 368, it seems quite clear to me that at 50T, the aircraft is capable of going higher than 370 all other things being equal.
Won't help you out of a jam I suppose, but I believe it demonstrates the articial nature of the limitation in question.
That a breach of this limitation should even be considered akin to a breach where a TCAS RA was ignored is lamentable.
Joined: Jun 2001
Posts: 2,627
Likes: 2
From: UTC +8
Isn't there a little paragraph in your FOM (Flight Operations Manual) that says something to the effect that: "Policies, checklists and SOPs cannot address every conceivable inflight situation, and that pilots are not restrained from exercising good judgement and common sense?" 
Joined: Jun 2004
Posts: 1,843
Likes: 0
From: Australia
Good one Glueball,
In an earlier airline, which was run by pilots, at the foot of each page were printed the words "Nothing in this manual replaces good judgement in the field".
A few years before departing from that operator, the lawyers forced it's removal.
Sorry Belowclouds, that doesn't help you does it ? Good luck.
In an earlier airline, which was run by pilots, at the foot of each page were printed the words "Nothing in this manual replaces good judgement in the field".
A few years before departing from that operator, the lawyers forced it's removal.
Sorry Belowclouds, that doesn't help you does it ? Good luck.
Last edited by Old Smokey; 30th July 2004 at 20:42.
TCAS Climb
Joined: Aug 2004
Posts: 27
Likes: 0
From: UAE
Stay cool BC! You've done the right thing responding TCAS RA demand. Otherwise, on professional side of the subject, you would't have been "polite" as a Captain of that flight, would you? That's why our customers pay the bills - to be safe.... well, not only to be safe, but this is number one you've been trained for and are getting your salary!
Joined: Nov 2001
Posts: 223
Likes: 0
From: Kagerplassen
Hey BC,
First: You did the right thing. You saved your passengers and your own life.
When flying A320, I was taught (I believe by the same people who trained your trainers, can that be?) that the FL391 restriction was due to the pressurization-certification. I know of a case where a captain on our fleet climbed to FL410 without any pressure problems.
A "colleage", who happened to be on the same frequency, telexed the company (instead of warning the before mentioned captain). The CPT was told by our fleet manager, that Airbus -due to the certification- just cannot guarantee enough pressurization at that level.
I doubt the oxy masks can cause the limitation. We use the same on our 340s, which are allowed to climb to FL410 (it only takes hours to get there... sigh).
One thing is for sure: There is no aerodynamical limit at FL391 for the 320-family, nor is the 320-family performance-limited at FL391. Flying in FL400 for a short while is no problem at all.
Shortly climbing to FL400 to adhere to your TCAS-SOP (=standard operating procedure!!!) is IMHO the absolute safest course of action.
Keep strong, keep safe!
P77
First: You did the right thing. You saved your passengers and your own life.
When flying A320, I was taught (I believe by the same people who trained your trainers, can that be?) that the FL391 restriction was due to the pressurization-certification. I know of a case where a captain on our fleet climbed to FL410 without any pressure problems.
A "colleage", who happened to be on the same frequency, telexed the company (instead of warning the before mentioned captain). The CPT was told by our fleet manager, that Airbus -due to the certification- just cannot guarantee enough pressurization at that level.
I doubt the oxy masks can cause the limitation. We use the same on our 340s, which are allowed to climb to FL410 (it only takes hours to get there... sigh).
One thing is for sure: There is no aerodynamical limit at FL391 for the 320-family, nor is the 320-family performance-limited at FL391. Flying in FL400 for a short while is no problem at all.
Shortly climbing to FL400 to adhere to your TCAS-SOP (=standard operating procedure!!!) is IMHO the absolute safest course of action.
Keep strong, keep safe!
P77
Joined: Mar 2003
Posts: 563
Likes: 0
From: Tea green International
Gulfstream 550
On this highly automated aircraft, which Gulfstream claim has had vast flight crew input, there are still one or two odd balls.
For example, in the event of a engine failure, the crew must manually change to TA only.
The reason given being that the "computers" do not know the aircraft is sinle engine. And there might not be enough power, etc, to make the required climb.
I am very surprised that this consideration is not built into the software.
In relation to the main thread, has single engine situation, been built into Airbus TA/RA situational awareness.
For example, in the event of a engine failure, the crew must manually change to TA only.
The reason given being that the "computers" do not know the aircraft is sinle engine. And there might not be enough power, etc, to make the required climb.
I am very surprised that this consideration is not built into the software.
In relation to the main thread, has single engine situation, been built into Airbus TA/RA situational awareness.
Joined: Sep 2002
Posts: 2,188
Likes: 6
From: La Belle Province
AC20-131A "Airworthiness Approval of Traffic Alert and Collision Avoidance Systems (TCAS II) and Mode S Transponders" which may be found here provides a range of TCAS manoeuvres (in Table I of the "par3" file) which are to be met in order to permit the CLIMB RAs to be issued by the system. However, it is not considered necessary to meet the requirements as a steady-state manoeuvre - speed may be traded for altitude provided the various speed minima specified are respected.
Assuming Airbus used this guidance material, then of course adequate (aerodynamic) performance must exist to respond to the RA. Unless you're in an unusual configuration there should never be a concern that responding per the RA will cause any kind of handling/performance issues.
Assuming Airbus used this guidance material, then of course adequate (aerodynamic) performance must exist to respond to the RA. Unless you're in an unusual configuration there should never be a concern that responding per the RA will cause any kind of handling/performance issues.
