Missed Approach Climb gradient and missed approach requirements

[italia458]

LIN...

You learn something new every day! I wasn't aware that category speeds were determined in such a different way, especially for Canada's next door neighbour, the good ol' US of A! I personally think that it makes more sense to determine your category based on what you're actually flying the maneuver at that day and not a speed you're supposed to be at when you're 50' AGL. Obviously, as I have said before, it doesn't matter what speed you're flying a maneuver at... if you can keep the airplane within the distance limits for the protection area, you will be safe! - So the FAA and PANS-OPS rules aren't necessarily bad, but I would argue that the faster you go, the more distance you use to maneuver, therefore, having more distance available to you is the safer option.

I just don't think I have enough pull with the FAA or ICAO to make any sort of change like that though! And I am biased as I'm only really familiar with TP 308 and Canadian rules.

Why can't we all agree on using one set of rules? Isn't that why we have ICAO?

I agree! It isn't as if the airplanes flown in Europe, or the USA, or Canada operate under different physics requiring extra/different rules to ensure obstacle clearance. I would say it'd take a heck of a lot of work to get everything down to one ICAO doc that every country that's a part of ICAO uses.... an enormous amount of work!

[FlightPathOBN]

It is similar, in fact is is the same, as Canada uses the FAA criteria, virtually an exact copy...all of that design criteria that you showed is TERPS...not ICAO 8168...

The approach CAT is based on speed of the final segment. In both criteria.
I also dont understand the 50' reference to approach speeds. Neither TERPS nor PANSOPS uses approach speed at 50'...where is that coming from?

You have to have a CAT speed for the maneuvers, to make sure the aircraft stays within the prescribed containment areas.

As an example, circling approaches, the TERPS circling minimum provides 300 feet of obstacle clearance within the circling approach area. The size of this area depends on the category in which the aircraft operates.

Category A 1.3 – mile radius
Category B 1.5 – mile radius
Category C 1.7 – mile radius
Category D 2.3 – mile radius
Category E 4.5 – mile radius

PANSOPS uses a different value for the minimum obstacle clearance, hence the radius values are different, with the ICAO criteria being much more conservative (larger)

The differences in calculations for the approach are simple...PANSOPS uses a level section, while TERPS does not.

The other containment areas concepts are very similar between PANSOPS and TERPS, but again, with more conservative values, PANSOPS creates much larger containment areas.

One must remember that the FAA and Boeing have lead virtually all of the criteria.

Good example is RNP...developed and created by the FAA and very usable with 8260.52....when 'adopted' by ICAO, just try to wade through 9905 with all of the technical and other errors in the document....
why did ICAO decide to change all of the terminology?
There was an ICAO version 8260.52A floating around that was an FAA attempt to harmonize with the ICAO terminology..but..they had already worked up 8260.54A, which has the ICAO terminology...

As for the CAT speed difference, ICAO has higher speeds per CAT, most likely to keep more Airbus variants in a lower CAT, and therefore increase access to airports (many airports have CAT C limits on runways/procedures)

Why ICAO decides to 'adopt' the FAA criteria by modifying it to create virtually the same results, is a matter for the politicians, not engineers.

[9.G]

I'd surely be reading about the differences in determination of approach category when I fly to YVR or YUL, wasn't the case for the past years nor will it change in the near future. I have no desire to argue bout the semantics. Look here: the whole bloody world goes by one single rule and Canada doesn't. Don't think so. Simplest logic is the best approach sometimes.

[italia458]

FlightPath...

It is similar, in fact is is the same, as Canada uses the FAA criteria, virtually an exact copy...all of that design criteria that you showed is TERPS...not ICAO 8168...

Yes, TP 308 is closest to TERPS but it's not a 100% copy... very close though.

The approach CAT is based on speed of the final segment. In both criteria.
I also dont understand the 50' reference to approach speeds. Neither TERPS nor PANSOPS uses approach speed at 50'...where is that coming from?

PANS-OPS references Vat speed and TERPS references Vref speed - they are essentially the same. Look up the definition of Vref. It's the speed the airplane is to attain at 50' above the runway. On the final segment, usually operators will fly at REF +5 to REF + 10 and do a slow deceleration so as to reach REF at 50' above the runway. Reference FAR 25.125(b)(2).

I understand all the circling requirements and distances, etc.

I think this discussion is about the speeds and categories that are applicable for those speeds - and the determination of the speeds.

It appears the FAA and ICAO use the Vref or Vat speed, respectively, to determine the category that the airplane is to maintain. Canada does not. Canada's rules, as I have referenced, state that the speed at which you are flying the maneuver at will determine what category you are to maintain.

9.G...

Look here: the whole bloody world goes by one single rule and Canada doesn't. Don't think so.

You're in denial, 9.G. I've referenced the applicable documents to show you that Canada doesn't follow the same rules as the FAA and ICAO with regard to this issue.

[FlightPathOBN]

The CAT speeds are minimums per segment...

Sorry, but as a wholly owned subsidiary of the US, Canada just scrapes the name tag off the FAA order...

Dont you remember the other post?

From TP308 GPH209
Volume 6, Supplemental Criteria Construction
(1) Document 1 – Flight Management System (FMS) – Added
(a) Former US FAA Order 8260.40
(2) Document 2 – RNAV Departures – Added
(a) Former US FAA Order 8260.44
(3) Document 3 – Terminal Arrival Areas (TAA) – Added
(a) Former US FAA Order 8260.45
(4) Document 4 – Wide Area Augmentation System (WAAS) – Added
(a) Former US FAA Order 8260.50
(5) Document 5 – Required Navigation Performance (RNP) – Added
(a) Former US FAA Order 8260.51
(6) Document 6 – Precision ILS Category II/III (ILS CAT II/III) – Added
(a) Former US FAA Order 8260.61

[italia458]

FlightPath...

Canada is not a "wholly owned subsidiary of the US". We have VERY similar procedures but they are clearly not the same. Why do you think you're required to take an exam if you want to transfer your license to TC or FAA?

The CAT speeds are minimums per segment...

I understand that! It's written quite clearly in the FAA document you showed me. However, that FAA document DOES NOT apply in Canada!

You seem to refuse to believe or have trouble understanding that Canada does not follow the FAA rules on this issue! I've already showed you the applicable Canadian documents to prove that. What are you unclear about?

[9.G]

The discussion about a straight-in mins is theoretical anyway as they're all the same for all categories. Only the circle to land differ with the IAS.

[FlightPathOBN]

Aircraft are certified by the manufacturer for the Approach CAT.

Vref is based on several factors, with a baseline. Different weight and flap settings influence the actual value, and many operators will use CAT D for a CAT C aircraft when calculating an approach...
As an example, the Vref CAT C for a 737 is based on 40T LW with flaps 30...

The pilot must calc actual LW and flaps to determine to use the CAT C or CAT D approach...

[Capn Bloggs]

Haven't read the whole thread but:

Originally Posted by Flightpathobn

As an example, the Vref CAT C for a 737 is based on 40T LW with flaps 30...

The pilot must calc actual LW and flaps to determine to use the CAT C or CAT D approach...

That's not what the Australian AIP (ENR 1.5 1.2.1) says at all. The approach CAT is determined by the Vref at MLW in the approach config. You cannot reduce the Cat here because you are light.

[de facto]

As an example, the Vref CAT C for a 737 is based on 40T LW with flaps 30...

How did you/they come up with such a number?,my 737 DOW(no cargo,no pax,no fuel) is around 45T

On a side note,my airline aircraft that are Categorized as Cat C have always a VREF below 141kts with Flaps 40 NOT 30 and a go around flaps 15 below 160kts...food for thought

[BOAC]

Apart from his weights, FPO is surely correct? Any weight above MLW or 'abnormal' config could result in a higher Cat?

[Level Attitude]

Higher Decision Altitude

I found this thread quite interesting so wanted to add in my (probably
mis-informed) opinion and questions.

I'm looking from the perspective of Light Twin Piston flying in UK, so unsure
if ponts relevent to other countries, jets, more than 2 engines, etc.

If an MEP cannot obtain, or exceed, a 2.5% climb gradient with one engine
inoperative then planing (as far as practicable) should be based on SEP
criteria:

eg:
- No (commercial) departure if cloud base is below 1,000' above
airfield - to allow for visual obstacle clearance in the event of an EFATO.

- Do not descend below 300' above threshold unless you are committed to land:
ie Runway in sight, Runway available, Stable Approach and Landing
clearance received.
This implies that with an engine failure the MAP would be further back, and
hence higher, along the FAT. So if a missed approach was initiated the
2.5% obstacle clearance surface would not be breached even with a climb
gradient of less than 2.5%.

Only time there might be a problem is if you are on an all engine approach
and you lose an engine whilst fairly low on FAT - However your chances here
are still much higher than if you were in a single engine aircraft to
start with.

So if aircraft not capable of 2.5% climb on one engine should you not plan
your approach to a higher Decision Altitude?

[de facto]

Any weight above MLW or 'abnormal' config could result in a higher Cat?

I would think so yes.

[9.G]

Any weight above MLW or 'abnormal' config could result in a higher Cat?

-don't think it's the case for a straight in though.

[FlightPathOBN]

For the 737, Vref rule of thumb was based on 40T and flaps 30.

Then Vref can be est with -1 less/at than 40T and 3 kts above fl30

So at 40T, with flaps 30 equals 40x3-1=119kts as a standard Vref

for 40T at flaps 40 = Vref 30-3 kts or 116kts...

As you increase the weights, with flaps 30 as the ref...you get the actual CAT reference..

Regarding previous comments, I am not sure about ATC ops vs criteria in the US, but in all of the other places, from the IF inbound, if you go missed, you are required to follow the missed approach procedure (which may include descent because of crossing paths) and to harmonize with departures, LAHSO, etc...

[de facto]

Quote:
Any weight above MLW or 'abnormal' config could result in a higher Cat?
-don't think it's the case for a straight in though.

Yes it is,the CAT is based UP to MLW in a specific flaps config.


Flightpath,do you have a doc affirming the fact that flaps 30 was used to establish cat C or D?(what you call the 'ref'erence?).

[FlightPathOBN]

defacto,

You would have to look at your particular variant to see what they used as the reference for Vref CAT...usually I see it as the median weight, not MLW, with flaps 30. This sets the aircraft reference CAT,

Here is what Boeing supplies as the Ref CAT for the aircraft...you would have to back through the calcs to see what weight/flaps, to get that approach speed.
(I think a quick way is the check your QRH, I have one for the 737-700 right here...the Ref CAT from the Boeing table below is 129kts...looking at the QRH, that is a 55T flaps 30 match...


http://www.boeing.com/commercial/air...oachspeeds.pdf

[de facto]

I am not familiar with -700 but by memory a 737-900 has a flaps 30 VREF of 151 kts at MLW.(far from the 141 kts in the table you provided).
A -800 at max landing weight may have a flaps 30 Vref of 147-148 kts.
A -800 would have to be around 58-60 T at flaps 30 to have a VREF of about 142, quite below max LDW..

All aircraft in my airline with max ldw of 66360 kgs are cat D as in your table.

[Capn Bloggs]

Flt Path OBN,

I say again, in Oz, you CANNOT willy-nilly pick your category depending on your weight. The Cat is based on the MLW at landing flap. Nothing else. Is the rest of the world different?

[FlightPathOBN]

defacto, Bloggs,

The aircraft CAT is set by the manufacturer, and that is worldwide, note the table Boeing table from the previous post....

The CAT is NOT based on MLW, nor max flaps, for that ac. The ref CAT also does not include any winds. The manufacturers certainly play with the numbers a bit, but that is their call.

For your edification, I looked it up on the 737-800 QRH.

The Boeing cert table shows the 737-800 approach speed at 142kts....(MLW is 73T)
from the QRH, that is 60T flaps 30.