Can an ASDE altitude readout be used to verify a Mode C STARS readout?

[yup]

5-2-15. Ensure that Mode C altitude readouts are valid after ... initial track start ... except as follows: c. Consider an altitude readout valid when: 2. You receive a continuous readout from an aircraft on the airport and the readout varies by less than 300 feet from the field elevation.

So the ASDE shows the aircraft at field elevation. Now I know that the aircraft's Mode C readout is valid on the ASDE display. Great.

Can that validity transfer to a STARS target, or does the continuous on-airport readout have to be shown on the STARS display (CTRD) as well? They reference 5-2-21 and 5-14-5, terminal and enroute altitude filters respectively. ASDE doesn't have controller-settable altitude filters.

Assume that the radar site is not on-airport and the target has dropped off the ASDE display prior to appearing on the CTRD, so I can't compare the two Mode C readouts in real time. I would contend that that would fulfill the spirit of c3, but let's say I can't even do that.

 

[Ztron]

Just verify the altitude, I don’t understand. If the altitude info dropped off, wouldn’t you want to verify if the readout is correct?

 

[jaande11]

Don’t think so, but even if you could, why would you do that?

 

[MJ]

No. 3-6-3 states what an ASDE can be used for.

ASDE system derived information may be used to:

1. Formulate clearances and control instructions to aircraft and vehicles on the movement area.
2. Position aircraft and vehicles using the movement area.
3. Determine the exact location of aircraft and vehicles, or spatial relationship to other aircraft/vehicles on the movement area.
4. Monitor compliance with control instructions by aircraft and vehicles on taxiways and runways.
5. Confirm pilot reported positions.
6. Provide directional taxi information, as appropriate.

 

[yup]

Just verify the altitude, I don’t understand. If the altitude info dropped off, wouldn’t you want to verify if the readout is correct?

Fair point, I would.

Don’t think so, but even if you could, why would you do that?

Because the .65 seems to say I can, maybe, and it would save me the five seconds of asking the aircraft to "say altitude." Mostly I'm curious about how the procedure works and why they mention it in the book.

It says that I can use a continuous on-ground readout which matches the field elevation, but STARS doesn't/shouldn't give you that continuous readout because if the system picks up someone squawking on the ground it will activate their flight plan and cause issues. So what system does give that readout? ASDE. So can the Mode C validation transfer from ASDE to STARS or it is a useless procedure? It wouldn't be the first time I've come across a seemingly useless procedure.

No. 3-6-3 states what an ASDE can be used for.

Okay, now I see. Compare 3-6-3 to 5-14-3. You can use STARS for "altitude information" but they don't say you can use ASDE for that.

Kinda makes you wonder why ASDE includes a Mode C field in the data block, but whatever.

 

[Seeyoufly]

Fair point, I would.


Because the .65 seems to say I can, maybe, and it would save me the five seconds of asking the aircraft to "say altitude." Mostly I'm curious about how the procedure works and why they mention it in the book.

It says that I can use a continuous on-ground readout which matches the field elevation, but STARS doesn't/shouldn't give you that continuous readout because if the system picks up someone squawking on the ground it will activate their flight plan and cause issues. So what system does give that readout? ASDE. So can the Mode C validation transfer from ASDE to STARS or it is a useless procedure? It wouldn't be the first time I've come across a seemingly useless procedure.


Okay, now I see. Compare 3-6-3 to 5-14-3. You can use STARS for "altitude information" but they don't say you can use ASDE for that.

Kinda makes you wonder why ASDE includes a Mode C field in the data block, but whatever.

I could be wrong, but I believe asde pulls the attitude from mode c anyway, therefore still isn’t verified….

 

[TimShady]

I could be wrong, but I believe asde pulls the attitude from mode c anyway, therefore still isn’t verified….

It is if the readout is 600 and your field elevation is 600 and they’re on the ground…
I guess you could ask the pilot at say altitude just to be sure.

 

[MJ]

Stars mode c readout is valid if it’s observed at field elevation. That’s the basis of op question.