Go Back  PPRuNe Forums > Flight Deck Forums > Tech Log
Reload this Page >

G/A below minima

Tech Log The very best in practical technical discussion on the web

G/A below minima

Old 12th Feb 2010, 12:10
  #21 (permalink)  
Thread Starter
 
Join Date: Feb 2006
Location: Europe
Posts: 102
Likes: 0
Received 0 Likes on 0 Posts
What aircraft?

Does it matter? We had 9 different fleets in the company all CAT C or D.

BLIP- Spot on.

The company flew to over 900 destinations all over the world and the point made to us was- When breifing the approach have a look at your "flygprestanda" for OEI procedure as it may differ from your missed approach and that could be your life insurance if a go around below minima is required. Reasons for which could be numerous. Fire trucks on the runway due to you declaring an emergency with the OEI could be one. I do not think it would make a big difference hitting a fire truck (or more) or hitting a moutain- the outcome would be the same I think

Accountant? I am terrified to hear that commercial pilots (assuming that they are) advocate making up procedures or just do not worry about worst case scenarios.
Seriously! If your level of professionalism is as reflected in your posts I am worried!
Blackcoffeenosugar is offline  
Old 12th Feb 2010, 12:50
  #22 (permalink)  
 
Join Date: Jun 2001
Location: Boldly going where no split infinitive has gone before..
Posts: 4,783
Received 44 Likes on 20 Posts
despegue,

As I'm sure you're finding out from reading here, it is indeed considered SOP by many operators to know the EOP for the runway you are landing on, particularly if you are SE and know there are terrain issues in the go-around.

Kirks Gusset,

You are not guarenteed making required climb gradient S/E for the Missed Approach from the minima, let alone below it. And I don't mean in a piston twin. I fly 777s, and even the -300ER won't make 2.5% under some conditions, and there are also approaches with higher than standard gradients required.

Under those circumstances you are stuck either with higher minimas, or the requirement to plan a non-standard MAP. In either case, the aircraft will not make required terrain clearence if you flew the standard MAP from below the minima.
Wizofoz is offline  
Old 12th Feb 2010, 17:00
  #23 (permalink)  
 
Join Date: Oct 2009
Location: UK
Posts: 1,270
Likes: 0
Received 0 Likes on 0 Posts
Hi Blackcoffeenosugar,

You are not expected to look at the take off performance and engine out procedure when flying an approach and GA, and ATC will not expect you to fly a SID, so my ANS = A.

The GA procedure's for PANS OPS 1, 2 and 3 plates assumed you could make 2.5% gradient initially, a level acceleration at a published acceleration altitude (or if non published then your company's standard AA) for 7 miles, and then a small +ve climb gradient with MCT set and clean. Most Pans OPS 4 plates don't include the performance calculation and it's up to the operator to choose his AA. The published initial turn on the GA, speeds to fly and tracks etc. should ensure a safe trajectory provided you can make the published gradient from your minimum.

Since you started the GA from below minima, you may be in deep poo.

If your calculated GA gradient is below the published figure (due overweight landing etc.), then you should have advised ATC that you would be unable to GA from the approach due performance, and have received "Landing Assured" before you commenced the approach.
rudderrudderrat is offline  
Old 12th Feb 2010, 23:38
  #24 (permalink)  
BarbiesBoyfriend
Guest
 
Posts: n/a
If this should happen to you- Clearly you are having a day that no approach plate writer foresaw.

Fly your aircraft and do your best. No plate can help you.

When weird stuff happens-and it does. You will get ZERO help from books or plates.

Instead of worrying about unlikely (in fact, so unlikely that it will probably never happen to anyone) **** like this, learn to hand fly your a/c to a good standard. Or do some other useful work.

Either that, or..................accountancy!

Remember. The books are there so the company can kick your ass. If you think they are there to help you? Think again...it's not the whole story.

On reflection, I suppose your hypothesis could have some value in the SIM.

But do you think, it could ever happen in real life? And realy.................is it ever likely to GETCHA!
 
Old 13th Feb 2010, 09:32
  #25 (permalink)  
 
Join Date: Nov 2002
Location: Dublin
Posts: 652
Likes: 0
Received 0 Likes on 0 Posts
Wizofoz, In circumstances where the net climb gradient for the missed approach is not guaranteed, the landing weight is reduced or the minima is higher, we have already stated that. I flew 777 as well, so please advise me when I can't make the gradient taking into account the above.

Balckcoffeenosugar, The missed approach should commence at the MAP. The EO sid commences after take off at the DER. How do you propose to get from the MAP back onto the EO sid. The screen height and terrain clearance from the EO sid is MORE restrictive as it assumes a starting position of zero ft on the runway, not from a MAP height of perhaps 200'.

Looking at typical cases, Geneva, Dalaman,the landing weights are all restricted and there are two minima for different climb gradient, I fail to see where the problem is unless the restrictions have been overlooked.

The 2.5% net climb should be achievable.

In cases where the GA performance is questionable, eg gear no retraction, the approach should not be commenced unless a landing is assured.

The problem with all this stuff is that it is theory and sensible airmanship will prevail, but if you are not following the std missed approach procedure all terms of refference are lost at a time of high workload.
The other consideration here is speed, some missed approach and EO sids, eg CMF are based on a fixed speed to keep the a/c within the protection area, carrying out a missed approach and then trying to get on the E/O sid.. pray tell.

Blackcoffeenosugars, what do your SOPs state?
Kirks gusset is offline  
Old 13th Feb 2010, 09:53
  #26 (permalink)  
Thread Starter
 
Join Date: Feb 2006
Location: Europe
Posts: 102
Likes: 0
Received 0 Likes on 0 Posts
Dear Kirk

You seem to have missed the part about this being a go around/ balked landing below minima (regardless of which ones). You are in fact closer to the DER than to the MAP. Also- the fact that you are slightly higher and faster than you normally would be at DER following would improve you chances of making the minimum gradient there is no shame in making a better gradient?
May I suggest that you read BLIPs post again.

SOPs, as per my previous statement, all the pilots I discussed this with were trained to the same SOPs. There was however (at that time) no specific reference to G/A below minima with an engine out.

Ken- you frighten me. Yes I have had it in the SIM. What do you know about my stick&rudder abilities anyway? (I haven't flown with you, have I? )
Blackcoffeenosugar is offline  
Old 13th Feb 2010, 10:08
  #27 (permalink)  
 
Join Date: Jun 2001
Location: Boldly going where no split infinitive has gone before..
Posts: 4,783
Received 44 Likes on 20 Posts
I flew 777 as well, so please advise me when I can't make the gradient taking into account the above.
1) When below minima, the point of this whole thread.

2) When reducing landing weight involves jettisining all ones fuel plus more- not always optimal!!!

In cases where the GA performance is questionable, eg gear no retraction, the approach should not be commenced unless a landing is assured.
No landing is EVER 100% assured!!
Wizofoz is offline  
Old 13th Feb 2010, 10:27
  #28 (permalink)  
 
Join Date: Sep 1998
Location: wherever
Age: 55
Posts: 1,616
Likes: 0
Received 0 Likes on 0 Posts
Note that the aircraft is certified for 2.1% approach climb gradient (twin oei) not the 2.5% that the procedures may be designed to.
FE Hoppy is offline  
Old 13th Feb 2010, 10:36
  #29 (permalink)  
 
Join Date: Nov 2002
Location: Dublin
Posts: 652
Likes: 0
Received 0 Likes on 0 Posts
Blackcoffeenosugars, I'm confused now! I just stated that the go around from the MAP must be less restrictive as you have a better climb gradient as you have more height and distance. Hence there is no reason not to follow the published missed approach,your climb gradient is assured if you follow the profile.
The Go Around point, even below minima, cannot possibly be closer to the EO SID than the DER. Most runways are 2 miles long, the MAP for an NPA will be 2 miles this side, for a CAT 1 .75 miles, thats at least 2.75 miles before the start of the EO side, probably more, as the first segment will add another mile, advantage at least 3 miles, or XXX feet in altitude.

For a balked landing SE? once the wheels have touched? never, never.

We do not have to follow the EO sid for the Go Around from the same runway we departed for instance as we are already at V2 and the performance allows for the normal SID.

Probably, the reason there was no discussion on go around below minima is that there is no legislation to cover this, other than, don't go below minima unless you have the required viusal refferences to land.

Rudderrudderrat is quite correct in the statements made.

Blips opinion, it's a debate, he's entitled to it, it's not approved or recognised and has practical problems, no LNAV available for instance, unless you know an FMS where I can sequence a departure E/O sid following an approach?
Where no circle minima is published, rules are found in PAN OPS, it's not a guessing game here.
The suggestion you are below minima in the first place implies IMC conditions and the visual terrain avoidance hmm?

Wizofoz, In the cases you sited, Dumping fuel, I am assume you are reffering to an return to land or diversion possible overweight landing.
For clarity, In terms of your opinions to the three scenarios presented in the original post..what course of action are you suggesting.. an Non Standard missed approach was not one of the options.

FE Hoppy, the minimum certified perf is 2.4% at V2, obviously if you are below V2 this will not be guaranteed.

Last edited by Kirks gusset; 13th Feb 2010 at 11:17.
Kirks gusset is offline  
Old 13th Feb 2010, 11:24
  #30 (permalink)  
 
Join Date: May 2003
Location: Liquifaction Island
Age: 64
Posts: 157
Likes: 0
Received 0 Likes on 0 Posts
//////////

Last edited by turnandburn; 15th Oct 2012 at 07:45.
turnandburn is offline  
Old 13th Feb 2010, 12:05
  #31 (permalink)  
BarbiesBoyfriend
Guest
 
Posts: n/a
Blackcoffeenosugar.

Heck! You scare easily!

Plainly, old chap, I've no idea at all about your hand flying skills. You could be the next Bob Hoover for all I know.

I've met plenty of folk who are ****-hot in the books before though, and lets just say that they're not always the most capable in the cockpit.

There's more important stuff than this obscure bollocks, to worry about!

IMHO, of course.
 
Old 13th Feb 2010, 12:11
  #32 (permalink)  
 
Join Date: Aug 2000
Posts: 1,499
Likes: 0
Received 0 Likes on 0 Posts
I fly into airports surrounded by high terrain on a regular basis. I suspect some of the answers here come from pilots who do not.
Staying on a SID will not protect you if you lose one engine, not during take off, not during MISAP from above or below minima. It MAY be OK, but you don't really know.
The MISAP procedure will protect you in the event of a single engine MISAP from minimums. It is designed to do this, and if you have terrain issues you will have different minima depending on your weight/performance. You need to check this during planning, and if needed, the weight must be limited.
If you go around from below minimums on a single engine you need to stay on your take off E/O procedure. And. yes, I have this procedure available when I fly into any of these airports. It doesn't say anywhere that I HAVE to, but my @ss is in the aircraft, and my objective is to keep it safe.
ManaAdaSystem is offline  
Old 13th Feb 2010, 12:15
  #33 (permalink)  
Thread Starter
 
Join Date: Feb 2006
Location: Europe
Posts: 102
Likes: 0
Received 0 Likes on 0 Posts
Dear Kirk (again)

The scenario has you below minima- which you would be if you had the required references and was attempting to land, but then some thing happens that forces you to go around. Be it fire trucks on the runway, another aircraft on the runway (for whatever reason) etc.

The point is you have gone below with intentions to land and now you can not land.

I am not advocating busting minima for fun or not following a missed approach if a missed approach profile can be followed.
In the scenario you have to come up with a good solution fast.
We are now discussing it on an internet forum and can have different solutions and have the luxury of time to discuss them. This way if the scenario should present it self in the future one will hopefully have "experience" in figuring out a solution.

With regards to LNAV- RNAV is not allowed with pilot defined waypoints, but the procedure could have NAV aids and radials to follow. AND this is an Emergency!
On the Airbus you could as an example enter the OEI SID in Secondary flight plan.
On the Boeing you could enter the points after your missed approach (with a discontinuity) and line select/sequence the first waypoint if you go around below minima.
On PROLINE 21 you could do the same as on the Boeing or use FIXes (provided you have enough FIXes available) the latter would require you to fly in HDG but the MAP presentation will be pretty dxxn good.

IF you choose to follow the SID you might not make the required gradient because of you weight or just because you are SE even with the better starting point (V2++) Higher than AFE and at least at the other end of the RWY.
IF you attempt to get back up on the missed approach profile you might not make the required gradient because you are lower and further along i.e passed the MAP.

IF you fly the engine out procedure (EO SID) you already have more altitude and speed than the procedure assumes (as you are already airborne before the runway starts) and this could make up for the fact that you are heavier.
And there are to my knowledge no EO SID with a higher gradient requirement than a SID?
This solution is only do-able provided you have looked at it whist briefing the approach in the first place.
Blackcoffeenosugar is offline  
Old 13th Feb 2010, 13:43
  #34 (permalink)  
 
Join Date: Sep 1998
Location: wherever
Age: 55
Posts: 1,616
Likes: 0
Received 0 Likes on 0 Posts
Kirks gusset:

CS25.121

(d) Approach. In a configuration corresponding to the normal all-engines-operating procedure in which VSR for this configuration does not exceed 110% of the VSR for the related all-engines-operating landing configuration, the steady gradient of climb may not be less than 2·1% for two-engined aeroplanes, 2·4% for three-engined aeroplanes and 2·7% for four-engined aeroplanes, with – bla bla bla bla

Take off climb second segment is 2.4% at V2

You have no idea what V2 is on final approach. You do know exactly what Vac is. I'm quite sure that in the case of a go around most pilots would follow their fight directors which will in most modern jets guide to Vac in the single engine go around case.

Vac gives a 2.1% gradient or 2.5% Cat II/III
FE Hoppy is offline  
Old 13th Feb 2010, 15:26
  #35 (permalink)  
 
Join Date: Nov 2002
Location: Dublin
Posts: 652
Likes: 0
Received 0 Likes on 0 Posts
I agree with all that Mr Hoppy, however one slight exception: we do know what V2 is on final approach, Vref for current flap setting is V2 for the GA flaps at 1.3VS. so Vref 25 is V2 20.
I'm prepared to be corrected here, but I thought the approach climb gradient of 2.1% was without reconfiguring,i.e with landing flaps, which is why it is more penalising than the 2.4% certification requirement..any thoughts?
That's enough thread creep for me, in the revised situation, we find ourselves half way down the runway s/e at 5o feet, then flying the EO sid may be worth considering, if we GA at the MAP, its the standard missed approach.
Kirks gusset is offline  
Old 13th Feb 2010, 16:29
  #36 (permalink)  
 
Join Date: Jul 2006
Location: On an aeroplane
Age: 54
Posts: 27
Likes: 0
Received 0 Likes on 0 Posts
I'm nearly sure that there is a requirement that VREF is equal to or greater than V2 specifically to cater for this scenario.

How it is done may be manufacturer specific but that is a fundamental I believe.
safewing is offline  
Old 13th Feb 2010, 17:26
  #37 (permalink)  
 
Join Date: Sep 1998
Location: wherever
Age: 55
Posts: 1,616
Likes: 0
Received 0 Likes on 0 Posts
I'm not going to copy paste CS25 as it's available free for download.

Vac has no relation to V2. It may be that some manufacturers have tied the two together but each is independent and has it's own requirements. Some aircraft go around with flap settings not available for Take off and as such there is no V2 schedule for the configuration.

Landing climb is 3.2% all engines operating landing flap and gear down. This may limit Vref to a speed higher than the minimum stall margin. This is the case for the Ejets with flaps Full. So much drag that to make the landing climb requirements they had to increase the Vref speeds.
FE Hoppy is offline  
Old 13th Feb 2010, 22:13
  #38 (permalink)  
 
Join Date: Jan 2003
Location: Outbound
Posts: 151
Likes: 0
Received 0 Likes on 0 Posts
Why isn't there an explicit SOP to deal with such situation?
Ask the training department?
Then you get''where is that written'' on a line check. Sound familiar?

Aviation is full of deficiencies and especially at airline level. That deficiency is often filled implicitly by the crew's skill and knowledge.They exercise judgement based on?
When they fail to fill this deficiency as some many here have clearly demonstrated in theory, then the airline has no option (due to ass covering) to put it down to pilot error.

For the real answer seek guidance from the Chief pilot and in writing, should you are unable to come up with an answer at the bar!
Sir Donald is offline  
Old 13th Feb 2010, 22:47
  #39 (permalink)  
 
Join Date: Jul 2006
Location: 'tween posts
Posts: 197
Likes: 0
Received 0 Likes on 0 Posts
prior prepration..

Blackcoffeenosugar,
Approach climb gradient(for twins) is 2.1%.assuming
S.E.;G/A FLAPS;L/Gup;live Eng at max avail thrust.
For cat II and above the requirement is 2.5% from Airfield elevation.
Before commencing an approach if it is determined that 2.5% can be met then there is no problem flying the published G/A even if initiated below cat I minima since all charts are based on 2.5%(those that require higher, are stated on the chart.)
hope that answers your concern about a G/A below minima.
In situations where you cannot meet 2.5% or the specific gradient required at some airfields, the crew can, with prior advice to ATC (preferably before commencing the approach) choose to fly the E.O.sid for want of a better option.
hope that helps
cheers
gearpins is offline  
Old 13th Feb 2010, 23:33
  #40 (permalink)  
 
Join Date: Aug 2008
Location: Betwixt and between
Posts: 666
Likes: 0
Received 0 Likes on 0 Posts
Approach climb gradient(for twins) is 2.1%.assuming
S.E.;G/A FLAPS;L/Gup;live Eng at max avail thrust.
For cat II and above the requirement is 2.5% from Airfield elevation.
Do you have a reference, as that is not what 8168 says? It says a nominal 2.5% from minimums.
Sciolistes is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.