Vector SID- Direct to First Waypoint

[emerydc8]

http://www.mypetwarehouse.com.au/peters-pasture-hay-2kg-p-8563

[Britjet]

Ordered!

[Britjet]

Tested in the BA sim. This doesn't happen.
I find it difficult to believe this would be an "option".
Sock order cancelled!
Peter.

[emerydc8]

Thanks, Peter. Did you try this on 31L at JFK?

[Britjet]

It was 13L.
Peter.

[Hardy Heinlin]

I see no VECTORS for 31L or 13L.

[Britjet]

I used the Kennedy 3 13L SID which has a vector, (straight ahead, I think) and then put MERIT as the next line.
Peter.

[Hardy Heinlin]

Ah, right. I was thinking of arrivals.


|-|ardy

[emerydc8]

I talked to a friend at Atlas who just did a PC in Miami and he said the sim check airman showed him a technique to fly LNAV direct to the first waypoint on a vectors SID. He demonstrated that on a vector SID, you can remove the VECTORS condition and bring the direct-to waypoint up to 1L of the LEGS page by pressing HDG SEL once. A second push of the HDG SEL engages LNAV and takes you direct to the waypoint. He tried this in the airplane last week and said it works. Go figure. I wonder if this is a customizable option or maybe a later software update.

Jon

[Hardy Heinlin]

747-400?

[emerydc8]

Yes. Sim and aircraft.

[Hardy Heinlin]

I'll add this as an option.

When you press HDG SEL a second time to engage LNAV, will the direct-to leg geometry be updated for the present position? If not, and if the aircraft has departed from the original direct-to leg, LNAV might not be on an intercept heading ...

Or will the first HDG SEL push keep the direct-to geometry in a dynamic MOD status, and the second push will activate the MOD?

[emerydc8]

I think it's the later, but I'll see if he can check this out in the airplane.

[EDIT]:

I talked to my friend again about this. He tried it in the airplane on the Ventura departure from 25L. The captain he was flying with had never heard of this so he showed him how it worked. There were two magenta lines -- one going straight out and the other starting at VTU. He doesn't recall what happened with the CDU because he wasn't watching it, but one press of HDG SEL took it out of LNAV and into HDG SEL on the FMA. The second push joined the two lines and LNAV went active again, which took them direct to VTU. I know this doesn't answer your question, but he's 100% sure it did this in the sim during his LOFT (his instructor excoriated him and his sim partner for not knowing it) and it did it on the 744F with the legacy software out of LAX.

I wonder if Peter can check this in the big sim if he gets a chance.

[Britjet]

I tested it before and it didn't work, but I will try and find time to test it again, this evening possibly - this was before or after getting airborne, by the way?
I must say I find it extremely strange that pressing a button on the MCP engages a different mode altogether.
Peter.
Out of interest thus doesn't happen in the 777 or the 787 either in BA sims.

[Hardy Heinlin]

When you're flying with VECTORS active, will the magenta vector line on the ND always start at the aircraft nose, no matter where the aircraft is, and will the line be aligned with the aircraft heading, and will the last waypoint and leg be removed? I think I've seen this somewhere, but can't remember whether it was a 744.

If the answer is yes, I guess the following happens with that new option:

1. Push HDG SEL: LNAV changes to HDG SEL; no other effect. Just standard technology. ND looks the same as before HDG SEL engagement. ND vector line sits on aircraft nose, independent of AFDS modes.

2. Push HDG SEL: Next waypoint activates, ND vector line disappears, ND direct-to curve and line to next waypoint appears, LNAV engages. MCP induced FMC changes are promptly active; no MOD status. (Just like an MCP induced FMC CRZ ALT change.)


|-|ardy

[Britjet]

I'm pretty sure that with vectors active the line starts at the aircraft nose and is aligned with the original vector direction, not the aircraft heading.
Peter.

[emerydc8]

I tested it before and it didn't work, but I will try and find time to test it again, this evening possibly - this was before or after getting airborne, by the way?

Thanks, Peter. This was after getting airborne. The test you did before was press HDG SEL then LNAV. Like Hardy said, it could be that the first push of HDG SEL does nothing to the CDU, so you wouldn't have noticed anything unless you pushed HDG SEL a second time. In any case, thanks for trying this out if you get a chance.

Jon

[Hardy Heinlin]

He doesn't recall what happened with the CDU [...]
[...] LNAV went active again, [...]

Theory: He didn't mean to say that the HDG SEL switch engaged LNAV. He just armed LNAV with the LNAV switch as usual, and thanks to the automatic activation of the direct-to-next-waypoint, the armed LNAV engaged promptly instead of staying armed due to any non-intercept heading.


|-|ardy


P.S.: A very nice feature, in my opinion. It's as ergonomic as pushing the MCP altitude knob to delete the next waypoint constraint etc.

[emerydc8]

He said he is positive he didn't touch LNAV. He just pushed the HDG SEL twice. The first push, the FMA showed HDG SEL. The second push of HDG SEL put it back to LNAV.

[Hardy Heinlin]

Maybe he armed LNAV shortly after engaging HDG SEL the first time, and then, during the vectors scenario, he didn't touch the LNAV button again? So, LNAV was already armed during the whole vectors scenario?