Why is the speed transition 240/10000 hard coded into the fmc? The speed limit is 250/10000 and it is not universal.

 

 

David Frank

Boeing codes 240 by default to account for stuff like unanticipated tailwind that could push the speed up. (the idea is to be conservative and not accidentally exceed it) And they're well aware it isn't universal - that's why it's a pilot editable field. It's that way in more places than not though so that's why they default it.

Boeing codes 240 by default to account for stuff like unanticipated tailwind that could push the speed up. (the idea is to be conservative and not accidentally exceed it) And they're well aware it isn't universal - that's why it's a pilot editable field. It's that way in more places than not though so that's why they default it.

 

I can't edit it. I can only change the SPD RESTR. I cannot change the SPD TRANS. Every entry gives me INVALID ENTRY on the fmc.

You can delete it though.

 

And you can enter 250/10.000 yourself.

 

but really, like Ryan said.....this is how it is in real life too.

To give a little buffer before you are "violating" a speed restriction.

 

As you know, Vnav Path means the aircraft will try to maintain its PATH.

If tailwinds are stronger than forcasted this means the aircraft will pitch down more to increase rate of descend. And this will increase your IAS. The "drag required" message will show telling you that you have to do something to avoid the speed increase (speedbrakes). You can easily exceed 250kt if you do nothing even though 240kt is in the FMC as a target limit, but at least you have a little buffer.

 

Same like driving a car.

When the speed limit is MAX 120km/hr we dont drive 128km/hr but we all drive 110-120 correct? ;-)

I can't edit it. I can only change the SPD RESTR. I cannot change the SPD TRANS. Every entry gives me INVALID ENTRY on the fmc.

 

You should be able to delete it, but from my understanding, you can't change it.

 

...haha - Rob beat me to it!

Jihaaaa....I beat Kyle I beat Kyle :-)

Jihaaaa....I beat Kyle I beat Kyle :-)

 

haha - during my "peak hours," (at work...shhhhh  :ph34r: ) too!

 

EDIT: Your "jihaaa" made me think of a random line that I'd heard before that was "party, party, yeah!" (Use a German accent for that.)  I was going to post it, but I didn't want to do so without a clip of the actual video...then remembered it was from a TedX talk, here (skip to 5:55 for the intro to the line - the line is at 6:15).  That guy is phenomenal, though, so you might want to watch the whole thing...

watched the whole thing :-)

 

Amaaaaazing, really cool !

 

thx.

I hate German accents ( :rolleyes:).

 

Paul McCartney once answered with a German accent during an interview: "(...) und itt vurked" (= "and it worked")

 

It's just so embarrassing for us ...   :blush:

 

 

It's just so embarrassing for us ...  

 

haha - I surprised some people at the German embassy one time by switching randomly to German.  A bunch of people from my high school went there for a concert (American students...not usually ones to speak German).  One of my friend's sisters didn't seem to be on the list of people that had been pre-cleared to attend, so I yelled across the parking lot "du bist nicht auf der Liste - geh nach Hause!"  The guards were rather confused as to who said that, but one of them, without skipping a beat, looked back in my direction (at my group) and just said "die...die Liste" and let her in anyway.

 

...and then I found $5.

atc does not care if you are going 252 or 255 knots because of wind. In fact if you are doing 240 indicated when you should be doing 250 they would get upset. Atc is very forgiving about the speed and on climbout if are heavy then you will almost always waive the 250 restriction anyway.

 

 

EDIT: Your "jihaaa" made me think of a random line that I'd heard before that was "party, party, yeah!" (Use a German accent for that.)

 

Somehow I feel you'll get a kick out of this: 

 

 

 

On topic: You can always delete. And remember, you are the pilot, not the FMS. When in doubt, revert to stick and rudder.

(...) a beat, (...)

 

 

 

Anyone who still remembers Boris Becker?   :P

 

https://www.youtube.com/watch?v=w_P3uwRiimo

atc does not care if you are going 252 or 255 knots because of wind. In fact if you are doing 240 indicated when you should be doing 250 they would get upset.

 

On the ground speed issue, you're kind of right.  It's only when your speed varies highly from the guy in front of, or behind, you that they might call you out.

 

Example:

The guy ahead of you is supposedly doing 250 and shows a groundspeed of 270 (tailwind, just for argument).  You're also supposed to be going 250, but you're showing a groundspeed of 290.  Unless it's going to cause a conflict, chances are, they won't say anything (or if they do, it'll be something non-accusatory like "AAL125, check your airspeed - I show you closing by 20 knots on the guy ahead of you," at least initially - unless they think you're an aircraft on a 117a or 117d exemption, where they'll just vector you around the lead aircraft).  If you're grossly over the limit (which can be seen in your closure rate against a lead aircraft), then they might be a little more pointed.

 

ATC are not police.  They don't report people for breaking regs because they might've seen you break one.  That's the FAA admin's jobs.  ATC will usually only report you if you did something against the regs that caused a situation that placed other aircraft in jeopardy (or if you're just being a complete [jerk]).

 

 

 

Atc is very forgiving about the speed and on climbout if are heavy then you will almost always waive the 250 restriction anyway.

 

If your user name is any indication, then you're a member from the United States.  Your statement is not at all true for that realm.  While, yes, they may be forgiving (see my point above - they're not the police of the skies), they cannot and will not waive the 250 knot restriction.  It is not within their scope of power to do so.  The regs are very clear on this.

 

FAR 91.117a gives exemptions for anyone who as obtained one from the Administrator (that's the highest level, and no lower).

FAR 91.117d gives exemptions for aircraft that have minimum safe airspeeds above 250 knots (this one is a bit of a grey point, because the FAA hasn't spoken to what defines minimum safe airspeed - clean or otherwise).

 

Those are the only two exemptions.

 

...unless you're going to invoke 91.3b.  Occasionally, in emergency conditions (a critically ill passenger, as an example), you may hear a pilot make some sort of request to ignore speed limits.  Again, a controller does not have the authority to wave the 250/10 rule.  He or she may only respond with "proceed as requested," or similar, as they cannot approve the request.  They certainly cannot deny it (emergency aircraft receive priority handling, and 91.3 allows a pilot to deviate from rules and instructions to the extent necessary to handle the emergency), but they cannot approve it, either.

 

Very common misconception.  Regardless of what you hear on the frequency, controllers in the United States are not approved to wave any part of 91.117a, b, c, or d.  Ever.

atc does not care if you are going 252 or 255 knots because of wind. In fact if you are doing 240 indicated when you should be doing 250 they would get upset. Atc is very forgiving about the speed and on climbout if are heavy then you will almost always waive the 250 restriction anyway.

Oh boy....and you know this because you fly for a living?

 

Whether ATC gets upset or not is entirely not the point.

It is a regulation. And as such, Boeing and airlines and Crew members will adhere to it.

And thus it is in the FMC per default.

 

You asked "why is 240kt in the FMC"

Which has been explained.

Now you are going an entirely different direction.

Maybe your question should have been "do you think the 250/10.000 rule is stupid?"

 

Ps good thing you are only flying in FSX where you can do whatever you want :-)

On they cannot and will not waive the 250 knot restriction.  It is not within their scope of power to do so.  The regs are very clear on this.

 

Very common misconception.  Regardless of what you hear on the frequency, controllers in the United States are not approved to wave any part of 91.117a, b, c, or d.  Ever.

Realy.....interesting. (mean that, not sarcastic).

I had no idea.

All over the world we often (like 50% of the time) get the "no speed restrictions below FL100" clearance. (sometimes during climb but more often during descend).

Dont remember now if I have ever gotten that one in the USA or not....

But you are saying they would never clear you that way?

 

Anyway, we then read back "no speed restrictions below 10.000" to the controller but fly 250 below 10.000 ft anyway.

Why?......because our airline regulations require us to fly 250kt max below 10.000 unless ATC explicilety requires us to fly a higher speed!

 

For one because it is a regulation and another (more important reason for me) is the risk of birdstrikes below 10.000 ft.