Speed restriction during descend

[Konrad Dolowy 1312245]

Hello

Lets [Mod - Happy Thoughts]ume it's a really busy day on VATSIM, there are many pilots in front of me and behind me heading to the same airport. Controller [Mod - Happy Thoughts]ings speed restriction to us so that we do not collide. I was told to maintain mach 0.78 or greater. No problem with that. Later, during descend, just to be sure I ask controller if the speed restriction is still valid - he says that indeed it is, "maintain 0.78 during descend".

Problem is, the more I descend, the faster I have to fly to comply with restriction - 0.78 at FL300 is maybe around 290 knots indicated, but at FL180 it increases to around 340 knots indicated, which is overspeed for b738.

What needs to be done in this situation? Do we "convert" mach to knots? If so, how do we do it and on what altitude? Or do we ask controller to change restriction to knots, but if so, again, on what altitude should we ask about it?

My aircraft is PMDG 737-800.

Thanks in advance

[Andreas Fuchs]

Hi Konrad,

 

indeed, ATC should have provided you with a speed restriction "on conversion". E.g. "maintain Mach .78, 320 knots on conversion".

[Josh Glottmann]

Yeah, you usually shouldn't be maintaining a mach number below FL240ish. Issue was on the controller's part, not yours.

[Sebastien Bartosz]

I'll usually say "Maintain Mach .78, 300 knots in the transition" or whatever the speed instruction may be.

Unfortunately though, many VATSIM pilots dont understand what that means. Good on you for catching it and asking the question!

[Andreas Fuchs]

It just means we have another topic that needs some education.

 

I wish we had a regular (e.g. half-yearly) email sent out to all active members (connected within the last 3 months), pointing out these kinds of things. You can never learn enough.

[Johan Grauers]

It just means we have another topic that needs some education.

 

I wish we had a regular (e.g. half-yearly) email sent out to all active members (connected within the last 3 months), pointing out these kinds of things. You can never learn enough.

 

That's a very good idea, I wonder what the higher vatsim leadership thinks? It could be done either on a global level (may be harder) or on a regional level (easier to align the email with the procedures of the region).

 

 

Konrad, well spotted and a good question to ask. I would suggest if it happens again report to the controller that you're unable to maintain the mach number (when you start to struggle or a minute or so before) and that should (in theory) prompt them to give you a new speed in knots instead.

[Andreas Fuchs]

I would make the request to ATC even more direct: "what INDICATED speed do you want me to maintain on conversion". I personally would not use the term "transition", because someone nitpicky could interpret it as the "transition level". Yeah, they exist. In all vACCs

 

Re the global/divisional email: I doubt that VATSIM would want to do this centrally, at least so far the doctrine of the BoG was to keep these kinds of "VATSIM NOTAMs" down to a minimum in order to not flood members' mailboxes.

I would welcome some kind of global message from VATSIM to all its members, outlining "best practices" and "recent hot topics" to keep everyone in the loop. For this to work we would have someone or a small group of people to create and manage the content.

[Sebastien Bartosz]

Yea I'm not a fan of the word "transition" in this case for the reasons you stated, I do believe it is US phraseology though. (I'd have to check the 7110.65)

[Christopher Liu]

I've never heard this phraseology before where I fly. Descent restrictions are almost always knots, Mach normally only used for high level cruise.

[Andreas Fuchs]

I've never heard this phraseology before where I fly. Descent restrictions are almost always knots, Mach normally only used for high level cruise.

Sometimes sequencing starts at high levels and then you'll need this technique. We grow with the things that we learn every day.

[Christopher Liu]

Well in fairness to myself I haven't flown a jet in a very long time, I can't remember the last time I went above FL250!

[Jack Colwill 815386]

Hey guys. The transition phase is a north American term and conversion is more European. The term transition is not confused in North America. The phrase it is usually used with is hard to confuse with anything else. "centre what speed would you like in the transition" is a common phrase. He knows you are referring to mach to indicated.

[Andreas Fuchs]

Yupp, for professional pilots who do this for a living, this is clear. And this forum thread will hopefully read by some VATSIM pilots who will remember know it next time they get this instruction. I love the free flow of information that we have here.

[Simon Kelsey]

Hey guys. The transition phase is a north American term and conversion is more European. The term transition is not confused in North America.

 

Hmm...

 

As with most US R/T - to a native English speaker, I'm sure not. To an ICAO level 4 aviation English (i.e. able to speak on the radio/SOP terms in the flight deck, but quite possibly not very fluent in normal conversation) speaker accustomed to flying in parts of the world where transition levels can vary wildly -- I wouldn't be so very sure.

 

To spin it the other way around -- "QNH 990" wouldn't be at all confusing to a UK/European pilot (or indeed across most of the world). But in the UK at least (if not across ICAO) the phraseology is "QNH 990 hectopascals" (added for any QNH below 1000) -- because there were several incidents where US-based pilots set (e.g) 29.90 inches -- about a 700 ft difference in true height. The addition (or removal) of just one word, or a slight change to a phrase can make a big difference in understanding, especially when airspace users of all sorts of different nationalities, levels of English proficiency and background in terms of experience and what they are used to hearing and working with are involved.

 

It's very easy for all of us to [Mod - Happy Thoughts]ume that others will know what we mean when we say something, but history tells us that is not always the case, sometimes catastrophically so in aviation -- and as such it's important to always be thinking about how someone might misconstrue what we're saying...

[Robert Shearman Jr]

Hey guys. The transition phase is a north American term and conversion is more European. The term transition is not confused in North America.

to a native English speaker, I'm sure not. To an ICAO level 4 aviation English (i.e. able to speak on the radio/SOP terms in the flight deck, but quite possibly not very fluent in normal conversation) speaker accustomed to flying in parts of the world where transition levels can vary wildly -- I wouldn't be so very sure.

While I do see your point, Simon, remember that in the US we do *not* encounter the fact that "transition levels can vary wildly" -- ours is fixed at FL180. So when hearing the word "transition" here a US-based pilot is not very likely to misinterpret it as a directive related to Transition Level.

 

Now, your point about non-native pilots flying in the US is a good one, & perhaps an example of an opportunity for the FAA to continue to "clean up" some of the key phraseology differences.

[Jack Colwill 815386]

I'm just wondering how an instruction of "transition to 290 knots" can be confused with anything todo with an altimeter setting. I fly both in north America and Europe and never have been confused with a speed restriction and anything altimeter related. But as for non English speaking pilots, there is lot more confusion than just speed restrictions that are a problem. The problem there is the requirement to speak and understand English is not high enough.

[Andreas Fuchs]

If you are an inexperienced pilot and you hear "garble garble transition 290 garble garble" then this can be confusing Even in the real world we sometimes make [Mod - Happy Thoughts]umptions of what ATC said and just give it a shot in our readback. If ATC is not happy, he will correct us or we will enquire again should the thing that we understood be confusing/odd.

 

It is more about what people know, expect and actively understand.

[Jack Colwill 815386]

I don’t know about anyone else but never in the real world will I make an [Mod - Happy Thoughts]umption of an atc clearance. I’ll ask my FO or Captain if they understood clearly and if neither of us did I’ll always ask for clarification. Never [Mod - Happy Thoughts]ume with a clearance.

[Andreas Fuchs]

I don’t know about anyone else but never in the real world will I make an [Mod - Happy Thoughts]umption of an atc clearance. I’ll ask my FO or Captain if they understood clearly and if neither of us did I’ll always ask for clarification. Never [Mod - Happy Thoughts]ume with a clearance.

You must be flying an old aircraft if you are the radio operator.

 

 

Man, in a picture perfect world you are right. Sometimes you think that you understood what was said and make a careful readback and wait for ATC to correct you - or not. We are NOT talking about critical items such as altitudes, headings, clearances. A speed instruction is not critical, there will be plenty of time to correct it or enquire later again. Better?

[Jack Colwill 815386]

Old aircraft? 737 NG, MAX, 767. ok maybe 67 lol.

 

Oh I think you meant I was the FE or something. I meant when I'm the PNF I'll ask the other guy. On the 37 I was captain. On the 67 I was an FO.

[Andreas Fuchs]

Wow, so you changed employer. At least at my outfit it is "once captain, forever captain, no matter what type".

[Jack Colwill 815386]

Nope same employer. Not sure where you are butI'm in north America. Most companies here are all seniority based. So you can hold 737 captain but doesn't mean you would be able to hold 777 captain. So you could have the choice of going 777 FO. Some might ask why someone would want to do that. In some cases, the pay could be better. Perhaps lifestyle.

[Andreas Fuchs]

Europe. Pay is the same on all types, it is the length of duty in the company that is deciding about this. Luckily.

[Robert Shearman Jr]

I don’t know about anyone else but never in the real world will I make an [Mod - Happy Thoughts]umption of an atc clearance. I’ll ask my FO or Captain if they understood clearly and if neither of us did I’ll always ask for clarification. Never [Mod - Happy Thoughts]ume with a clearance.

In the real world, you might have a situation where someone THINKS they heard correctly but didn't. But hopefully that's not common. On VATSIM you might well have someone who is embarr[Mod - Happy Thoughts]ed, for whatever reason, to admit they didn't understand, so will go with their best guess.

 

Even back when I was new I neeeeeeeevvvvvvvvvvveeeeeeerrrrrrrrrr did that...

[Mircea Pana 1427321]

ATC should provide you with the speed require however you have to maintain 250 knots bellow 10,000'.