... and maintain

[Redfox]

Hi,

why use US ATCOs (and some others) the phrase e.g. "ABC123 climb and maintain FL270" whereas in other countries the ATCOs use (only) "ABC123 climb FL270"?

Is there any "history" of the phrase "... and maintain" ?

Omitting this "add-on" will save time regarding freq occupancy ... so what's the benefit of adding these two words - compared to the "condensed" version?


Regards,
Redfox


ATCO: "The number is 220 - either reduce to it or make it your heading"

[Scott Voigt]

Because some suit decided that it was going to be in our book <G>... Can't think of any other reason for it... Of course, we can also use the term maintain XXX when they are going up or down and we want them to stop... We like the word too, <G> we use it for speeds as in maintain 320 knots or greater, or on the other side of the coin, maintain 250 knots or less stand by for holding <G>...

regards

Scott

[Giles Wembley-Hogg]

Redfox

I think you'll find that US controllers save RT time by missing out the words "climb" or "descend". An instruction to climb to FL340 would thus be "BAW123 maintain FL340".

It would also appear that "maintain" when relating to speeds does not necessarily mean "fly at this speed". See the thread entitled "Question for a US controller - 250kts <10".

Maintainingly yours

G W-H

[Cartman's Twin]

I fully appreciate that it's not your MATS Pt 1 standard but I do occasionally use it in the TMA, usually when I know the a/c will have to level as there's another chap descending to a 1000ft above. This is a precaution against the odd airline who assume they are going to receive continuous climb from departure and climb at 3000+ft/min till the last possible moment! Usually resulting in TCAS TA and occasionally RA's. I usually combine this with TI at the time of the clearance if I consider it appropriate.

If we consider an a/c is climbing or descending at such a rate that it will trigger an RA it is considered good practice to issue TI and if I know the RT is going to get rather busy I'd much rather get this out of the way early than face a TCAS TA at a time when I've hardly time to take a breath.

(And yes I also appreciate that adding 'and maintain' adds half a second to my transmission, but a TCAS RA and subsequent evasive manoeuvres take up a whole lot more and does nothing for my heart rate...)

[Redfox]

Cartman's Twin

that sounds very reasonable ...

I assume the "history" of this phrase has something to do with step climbs/descents - even at a pre-TCAS time ...


regards,

Redfox

[Cartman's Twin]

Quite possibly Redfox.

A number of our SIDS include stepped climbs to 3, 4 then 6000ft, so it could have a place when you clear an a/c to say 5000, cancelling the final level mentioned on the SID chart

[refplus20]

Anything that avoids the use of the word 'TO' must be good for non ambiguous RT.

[DirtyPierre]

Cartman's twin,

What a load of ****e. The phrase "and maintain" will not prevent a TCAS RA. The rate of climb/descent is what causes a TCAS RA. Version 7 of TCAS has since alleviated nearly all spurious RAs.

As for acft in a busy terminal environment being given intermediate levels, wouldn't it be better to give the PIC an estimate of how long before they can receive further climb/descent. Eg. QFA25 climb to F110, expect further climb in 3 minutes.

refplus20,

"To" should be used. Eg, "descend 5000 feet". Does this mean descend to 5000 feet or does it mean descend 5000 feet (ie. descend from F150 to A100).

A controller should also say eg. "descend to two thousand five hundred feet" and not descend to two five zero zero feet" as happened in one fatal crash.

Communication in air traffic control must be clear, concise and simple. Standard phraseology is set down and pretty standard throughout the world for a reason. Little add ons like "and maintain" do not aid good communication between ATC and the PIC.

[OVC002]

"A controller should also say eg. "descend to two thousand five hundred feet" and not descend to two five zero zero feet" as happened in one fatal crash."

Sorry, did you say descend 22500 feet or to 2500 feet. I think we should be told.

Descend/climb and maintain avoids any confusion

[spekesoftly]

Of course we Brits have our own quaint ways! ;)

"Climb/Descend to Altitude/Height 2500 feet"

[tug3]

Wouldn't bet next month's pay check on it, (Mrs Tug would kill me!), but believe ICAO rules may state the requirement for "climb/descend to and maintain...".

Some authorities/providers may be more strict in their interpretation/application of the ICAO RTF rules than others.

Rgds
T3

[Redfox]

As far as I can get it (see my location ;) ) the most commonly used phrases are

"climb/descend Flightlevel 230"

"climb/descend Altitude 5000ft"

No "maintain" and no "to" ... short and sweet ;) ... even so (nearly) no chance for any misinterpretation ... (???)

My assumption is that the "history" of the phrase "climb/descend xxxx and maintain" has something to do with step climbs/descents associated with wrongly adopted continous climbs/descents ... ( ? )

I also assumed that there were some "incidents" caused by such misinterpreted climb/descent instructions ... like the phrase "ready for take off" was amended to "ready for departure".

... or something like that.


regards,

Redfox

[DirtyPierre]

Descend/climb and maintain avoids any confusion

Bollocks!!!!

What will the PIC do after he reaches the level he is instructed to climb/descend to........um, maintain. So why say maintain?

In Oz we say flight levels for 11000ft and above, and feet for 10000ft and below. Similar to what the Brits use (ie. altitude/height). So an instruction to descend to A070 would be, " Descend to seven thousand feet". Where is the confusion?

[tobzalp]

The reason 'to' gets confusing is that some idiots chose to drop it. In my neck of the woods, the books say we must say 'to'. When there is variation between phrases confusion occurs.

[refplus20]

DirtyPierre. You seemed to have answered your own question. Descend, maintain 5000 feet sounds pretty clear to me.

:rolleyes:

[DirtyPierre]

Descend to and maintain.

Bit like saying, PIN Number. Or, looking back in history. No not confusing, just not required or necessary.

[Cartman's Twin]

Dirty Pierre

'What a load of ****e'.....

I fully understand what causes TCAS RA's. No confusion here thanks very much.

I feel if you'd actually taken a moment to think about what I said you'd understand how it may reduce the chance of said RA.

If the a/c know that they will have to level off due to conflicting traffic they are LESS LIKELY to climb at max rate until the moment they're about to bust their level. It may be different in your neck of the woods but some airlines here have a habit of assuming they will be climbing continously. With the additional information the a/c usually reduce their ROC as they approach their cleared level and THEREFORE no RA. In theory..

Less Black and White, more shades of grey..... We're all human


I've tried the "Climb FL120, expect further climb in 10 miles". The a/c climbed to twelve, and then climbed further after 10 miles.....

[OVC002]

OK, for the differently abled, let's try again.

"In Oz we say flight levels for 11000ft and above, and feet for 10000ft and below. Similar to what the Brits use (ie. altitude/height). So an instruction to descend to A070 would be, " Descend to seven thousand feet". Where is the confusion?"

Sorry, did you say "descend to seven thousand feet" or "descend two seven thousand feet"

It seems pretty obvious that confusion might occur from time to time.






chump

[DirtyPierre]

Sorry, did you say "descend to seven thousand feet" or "descend two seven thousand feet"

WTF?

Two seven thousand feet......Read the post again.

Flight levels for altitudes @ and above 11000ft. So 27 thousand feet would be transmitted as flight level two seven zero.

No confusion here in Oz.

[OVC002]

Another go,

Date: 19 FEB 1989
Time: 06:36
Type: Boeing 747-249F
Operator: Flying Tiger Line
Registration: N807FT
Msn / C/n: 21828/408
Year built: 1979
Total airframe hrs: 34000 hours
Cycles: 9000 cycles
Engines: 4 Pratt & Whitney JT9D-7Q
Crew: 4 fatalities / 4 on board
Passengers: 0 fatalities / 0 on board
Total: 4 fatalities / 4 on board
Airplane damage: Written off
Location: 12 km (7.5 mls) from Kuala Lumpur (Malaysia)
Phase: Approach (APR)
Nature: Cargo
Departure airport: Singapore
Destination airport: Kuala Lumpur-Subang Airport (KUL)
Flightnumber: 66
Narrative:
The Boeing, named "Thomas Haywood", was less than half loaded with textiles, computer software and mail when it departed Singapore. Approaching Kuala Lumpur, the crew were cleared to route direct to the Kayell (KL) beacon for a runway 33 approach. While on the NDB approach, the crew were cleared to "...descend two four zero zero..." which was interpreted by the crew as "...to 400...". The aircraft descended below minimum altitude and crashed into a hillside at 600 feet/180m msl just before reaching the Kayell NDB, where minimum descent height was 2400 feet. The Boeing hit treetops and started to break up until bursting into flames.
PROBABLE CAUSE: Non-standard phraseology was used by Kuala Lumpur ATC, causing the crew to misinterpret the instructions.







chump

[Northerner]

.............Which is why we use the word Altitude.

If you say Descend to Altitude four thousand (or whatever alt you might be using) then the 'to' is separated from the numbers by the word Altitude and should not therefore be confused. With fight levels I definitely don't say it. ( the word 'to')

I'm just going to check, but I'm pretty certain that was standard R/T.

Then again, I might go for a beer instead!:E :ok:
:\
Cheers,
N

P.S. In terms of the topic, I do say "and maintain" if there is going to be crossing traffic. Maybe it is belt and braces, maybe it's over the top, but I follow it with traffic information (the only reason I say it) as I think it gives the pilot information to plan his ROC/ROD accordingly for his passenger comfort as well as the TCAS thing.

"Keep smiling, it make people wonder what you're up to."

[DirtyPierre]

OVC002,

Thanks for the reference, that was the incident I was referring to. That incident changed our phraseology in Oz. We use the phraseology I have been referring to in previous posts and since the change there have been no similar incidents in Oz attributed to this type of misunderstanding.

Now as for "and maintain". I still maintain they are superfluous words in a transmission. If you don't need to say it, then don't say it.

[Contrary Controller]

We use "maintain" here in Canada, although I was surprised when I came over here from the UK that the Canadians do not instruct a pilot to "climb/descend". When instructed to "maintain" an altitude/FL, a lot of American carriers readback "descend/climb and maintain...". Surely, "climb/descend" should be standard control instructions wherever you are?

So what about the "climb/descend and maintain" dilemma. As DirtyPierre maintains, yes it is obvious that the ac will maintain a level on reaching and therefore "maintain" would appear to be superfluous!!! Surely, the same argument applies when using "descend to altitude 2000"? As you haven't used the words "Flight Level", isn't it clear that you are referring to an altitude?

"Climb/descend AND MAINTAIN" does have one major advantage. It is unambiguous, and that is a bloody good thing if you deal with so many foreign carriers whose command of English is not that great.

The point here is NOT to say that Oz and Canada have got it wrong, because they haven't. Both have their own RT procedures that work FOR THEM. That is the point! Surely, we should ALL be using one international basic standard?

[Jerricho]

Surely, we should ALL be using one international basic standard?

Yes we bloody well should.

[PPRuNe Radar]

Surely, the same argument applies when using "descend to altitude 2000"? As you haven't used the words "Flight Level", isn't it clear that you are referring to an altitude?

It could be a height, favoured by UK military airfields.

[Scott Voigt]

Jerrico;

You of course are right, we should all be using one standard, but you guys (and gals) don't want to change <big evil grin.>.

regards

Scott

[normally right blank]

Surely, the same argument applies when using "descend to altitude 2000"? As you haven't used the words "Flight Level", isn't it clear that you are referring to an altitude?
"descend to two thousand feet".

"descend to altitude 2000 feet, QNH 1015"

I know, it works for me.
(And I get two seconds more of "planning time")
(Yes, I was a non-standard "Bxxxxxx" in my younger years - just so many "say agains", will finally get to you :ok: )

It could be a height, favoured by UK military airfields. Are You sure? (Guess they are all at Fairford today!)

We've got QFE on our METAR, mostly for the Nord 262 ILS flight checker, which is now a Swedish B200 anyway and done on GPS.

QFE could be useful for f.ex. display work (see another thread hereabouts :uhoh: ) (And a certain T-bird F-16 incident :cool: )

Surely, we should ALL be using one international basic standard? And then there is that inches/hPa (mBar) thing.
Best Regards

[zzjayca]

In Canada, "maintain" isn't the superfluous word. "Climb/descend" or "cleared to" are the superfluous words. According to our Manops, all altitude changes are to be issued as: "maintain (altitude)" not climb/descend or cleared.

Proper phraseology eg:

ATC: "ACA123 maintain flight level three three zero."

ATC: "CFABC maintain one zero thousand."

[Redfox]

If I (as a pilot) hear from ATC:

"ABC123 maintain flight level three three zero"

(instead of "ABC123 climb [and maintain] FL330")

... I would wonder if the ATCO actually knows that I'm just flying at FL290 ... is he expecting me already at FL330 (which I should "maintain" for a while) ... ???

That's how it could get to european ears ... :)


regards,

Redfox

[Contrary Controller]

-------------------------------------------------------------------------------
In Canada, "maintain" isn't the superfluous word. "Climb/descend" or "cleared to" are the superfluous words. According to our Manops, all altitude changes are to be issued as: "maintain (altitude)" not climb/descend or cleared.

Proper phraseology...
-------------------------------------------------------------------------------

zzjayca - not arguing that point, but it is ONLY the Canadian standard. As Redfox states, it does has leave some room for interpretation, and surely we must have one common, unambiguous way of getting the instruction across. "Climb" and "descend" should be the key words here beacause that is exactly what you are telling the pilot to do.

Sorry to the Brits (especially the RAF contingent) out there. I didn't want to go in to the old QNH vs QFE thing.

[Jerricho]

I personally don't have a problem with the concept of the maintain thing (climb and descend are both recognised as standard phraseology in the Manual of Operations, but rarely used), however we did have a RAF Tornado come in a couple of months ago. On initial contact he was instructed to "Maintain 7000, altimeter 29.92". The pilot didn't descend. 1 minute later he was instructed to "maintain 7000". He read back he was maintaining FL 220. It was only when I suggested the controller talking to him instruct him to "descend to altitude" that he started down. The maintain was the confusion point.

Do I hold my breath till we get an international, standardised phraseology book that is to be used and enforced? I don't think I will.

[Contrary Controller]

Me neither. If "maintain" is what is I have to use then "maintain" it shall be!

I came up for air years ago on any kind of standardization... but there's no harm in dreaming!!!

[RustyNail]

My 2 cents worth, having used and taught standard ICAO RTF for the last 16 years:

The Climb, Descend and Maintain are 3 different things when refering to altitudes/levels.

You are either instructed to go up, go down or stay where you are.

Pilot: "BAW234 FL330"

Controller: "BAW330 maintain FL330"

If an A/c checked in and said "FL290" and was instructed to "maintain FL270" he would assume that the controller mis-heard his original call and say "we are maintaining FL290"

The use of "to" was brought about "down under" after several incidents where the instruction was vague and the pilots mis-understood the instruction.

"QFA45 descend 4000 feet" Does the A/c descend to 4000 feet or descend by 4000 feet??

The phrase Flight Level should be used for levels, and depending on the country, either Altitude 4000, or 4000 feet but there is no need for both Altitude and Feet, the instruction is clear enough.

The "climb to maintain FL330" is unnecessary, but if traffic is a factor then "climb to FL330, traffic is...." would give the crew a heads up on traffic affecting their climb, and would hopefully correlate with traffic on their TCAS. They can then adjust their rate of climb / descent accordingly.

While NavCan seems to want to be different, in a world where you are dealing with multi-national pilots in an ICAO based profession (ICAO are based in Montreal after-all!) all RTF should be ICAO standard.

In fact, it must be hard for NavCan management to justify any deviation from the standards and recommended practices of ICAO, at the end of the day standardisation (or lack of) plays a major part in safety related incidents.



:confused:

[zzjayca]

I don't agree that it should cause confusion. Maybe we Canadians think differently than "European ears". ;)

To me if the a/c is at FL290 and ATC gives an instruction to "maintain FL330" the only way I know of the a/c to get there is to climb. (could try descending, but it might get a little bumpy when you reach the earth's core). Conversely, if ATC gives an instruction to "maintain FL260" the a/c's only way of reaching the altitude is to descend from FL290.

Additionally, I don't see how you could interpret an instruction to "maintain FL330" as giving you permission to remain at FL330 for "a while" any more than if the instruction was phrased "climb FL330".

I realize that every/any phraseology if taken to the extreme may have an element of ambiguity to it, but in this case, if we are trying to eliminate words such as "to", maintain seems to be a reasonable choice. Using climb/descend or cleared, it becomes easy to slip a "to" in before the altitude.

So far, in the last ten years, I haven't had any European pilots misunderstand me when I use maintain.

[ferris]

zzjayca
To me if the a/c is at FL290 and ATC gives an instruction to "maintain FL330" the only way I know of the a/c to get there is to climb By that logic, why say "maintain"? If the instruction to "maintain" includes an inference that the a/c can climb, descend, or maintain a level, why say anything? Just say the level.

[PPRuNe Radar]

In English the word 'maintain' refers to something staying in a steady state (i.e. not changing). For that reason alone ICAO should scrap using a word which doesn't mean what it actually means in reality ;)

[Jerricho]

Wasn't there a TC Best Practice regardin the use (or non use) of "maintain"?

[West Coast]

As the mere receiver of these commands, I see no confusion.
I'm at FL330 and told to maintain FL250, I descend. Should there be much doubt?

[Jerricho]

Yeah, but Westy you're above average in the intelligence stakes ;) :ok:

The "maintain" issue seems to come into it in the UK where it has a totally different meaning. In Canada it is a command instruction, in the UK it is almost a "filling out" term. I know when I first came over here to Canada, it was a habit I had to get out of, simply because drivers on first contact would check in "descending to 7000" and I would reply "Roger maintain".......to be asked 30 seconds later what the cleared altitude was because the driver heard the word "maintain" and thought they missed the new altitude.

[normally right blank]

Strange but true:
This morning a colleague on "Approach" (same room) had a German Tornado at FL140 for a Hi Tacan approach (140,150,160 is "normal"). Several civilian airliners crossing and descending. He told the Tornado to "maintain 120 ", which got My Monday morning attention. (I was "Tower"). Sure enough - on the radar - they left 140 and asked: "Confirm descend to FL120?". "No! Maintain FL140!" (APP getting angry/confused: "Why the Hexx etc.". "Us" (the backing group (Tower and supervisor): "You said 120!". ;) "Did I?"

I'm told that our new VCS system has an instant "replay" feature, i.e. you "spool" back and check "what did he say" f. ex.

[spekesoftly]

So depending on your aviation background and area of operation, "maintain" can variously mean "climb", "descend", or "stay level" - beware! :ugh:

[Pygmie]

Correct me if I'm wrong, but aren't flight levels only used above 17,999 feet, i.e. starting at FL180? I thought the entire purpose of flight levels was to refer to altitudes in the standard pressure region where the actual height above the ground could vary significantly, hence why no mention of feet, and also to ensure pilots remembered to switch over their altimeters.

Do other countries have regulations for using the term Flight Level at lower altitudes? What is the reason behind this?

[West Coast]

Pygmie

It is indeed varied throughout.

Jerricho

Millions would argue otherwise, especially the wife...but thanks!

[Jerricho]

but aren't flight levels only used above 17,999 feet, i.e. starting at FL180?

Ah ha!! Not everywhere in the world mate. Christ, even in and around the London TMA there are different transition altitudes

FL40 - bah

;)

[DirtyPierre]

RustyNail,

completely agree with you.

BTW, there is standard ICAO phraseology. It is;

Instruction to climb/descend aircraft - "Climb/Descend to....."

In the event that confusion may exist - "Climb/Descend to and maintain......

This phraseology comes from the Australian AIP which sources it's information from ICAO documents.

In Oz we use flight numbers from 11,000ft and above, and feet from 10,000ft and below. Our transition altitude is 10,000ft. (Highest mountain in Oz is Mt. Kosciuszko about 7500ft high)

In English the word 'maintain' refers to something staying in a steady state (i.e. not changing). Exactly PPrune Radar. Why confuse things by using a word that means stay in a steady state to mean change to stay in a steady state?

Lets keep the instructions clear and simple by using words in a clear and simple way. KISS

[Scott Voigt]

Rustynail and others...

Don't be so rough on our neighbors to the north... They are using the same phraseology that we use here for the most part. We are not allowed to use just maintain for a climb or decent, but we are required to use maintain to tell them the altitude to stop at... Why??? As stated before, cause some suit decdied it a long time ago.

Now I do agree that ICAO states the requested phraseology to be used. But you have to remember that the rest of the world has less than half of the folks flying in the world. Between Canada and us, we pretty much have a lock on the numbers of pilots using the air <G>....

regards

Scott

[StillDark&Hungry]

Just a point

I was working on the WestEnd a few months ago, quite early in the morning, during the eastbound rush. I'd been up all night and the traffic was building rather rapidly so wasn't on top form.

We received an OLDI (electronic coordination message), and subsequent paper strip, from Shannon on a United into London at FL350. Running right with him, and garbling, was, from memory, an Air France at FL360.

As the RT was really crowded the united had tried to check in a couple of times but kept getting blocked. Eventually I had a gap, so jumped in with my usual;

"United xxx, London, Good Morning. Maintain FL350, direct NIGIT, Ockam 1F arrival"

From what I've read earlier in this thread I was a very lucky chap with his apparent Non-Standard (for a North American) reply;

"Thank you, Descend FL350 Ockam 1F arrival"

Thank goodness he'd said that - and not "maintain FL350" - I managed to quickly ascertain that he was actually at FL390, the level revision from Shannon had not been received, and that he should cancel the descent clearance.

Although a lot of factors combined to make a possible incident here it seems much more logical IMHO that a climb or descent instruction should be accompanied by exactly those words.

As for "Descend and maintain FL280" who cares! it may waste 0.25 of a second but it's not dangerous.

As for "Descend to 2 thousand feet" there is possible cause for confusion here as the KL example showed.

DirtyPierre, it looks as if you work in Brisbaine? Therefore you must get a lot of long-haul, tired, crews coming in. Surely you can grasp that a clearance such as;

"ConfusedAirways xxx Descend to three thousand feet, turn left to three two zero degrees, reduce speed to two two zero knots"

could cause mayhem in the cockpit and, worse still, a level bust etc.

P.S. You may think that's (in your words) "A load of ****e" or "Bollocks!!!!" but don't say that again you've expressed yourself fully in that direction enough times already. KISS I agree with- but it should be KISSS the middle S being Safe.

Rant over

[DirtyPierre]

Brisbane - no i.

ConfusedAirways xxx Descend to three thousand feet, turn left to three two zero degrees, reduce speed to two two zero knots"

Would never ever give anything like this to a pilot.


As for using "to"

Sorry, it is required. I've already outlined the why in previous posts. Read them. Never had any misunderstanding in Oz by using the word "to".