BeechTalk - BT

Username Protected · **Posted:** 12 Dec 2018, 00:32

Username Protected wrote:

How do we know the altimetry system error, though? Is that part of the pitot-static test, or something that must be certified during design?

Not clear as of yet.

It could be as simple as the OEM issues an SB that states the fact outright plus your altimeter correction card.

It could be something you test, by flying over an RVSM test station, for example.

Worst case, I suppose, is you could fly a static cone flight test and document it yourself.

https://en.wikipedia.org/wiki/Trailing_cone

Quote:

Why does ADSB enable this? I thought ADSB merely reported what the aircrafts altimeter was at. Does it somehow enable something external to verify the accuracy of that report?

Yes.

ADS-B reports both GPS and baro altitude. By comparing dozens of other aircraft in the area, you build a model of the error between the two. Thus you check your baro altitude error relative to the collective group of other airplanes flying in the same area. You can also mathematically model this from baro setting and upper air data.

In this way, any outlier aircraft with a large GPS to baro altitude error deviation is a problem, and should be denied RVSM usage.

The ADS-B altimeter check system is *WAY* safer than current methodology which is to try and assure compliance by design and periodic testing. Unfortunately, there was no check of true accuracy, so a plane could dangerously be off and hit another one until it is checked again. With the constant monitoring of ADS-B, there is no moment in time where a failure would go undetected.

Mike C.

Username Protected · **Posted:** 12 Dec 2018, 02:28

Username Protected wrote:

ADS-B reports both GPS and baro altitude. By comparing dozens of other aircraft in the area, you build a model of the error between the two. Thus you check your baro altitude error relative to the collective group of other airplanes flying in the same area. You can also mathematically model this from baro setting and upper air data.

Wouldn't it be easier to just use the GPS altitude and forget all about baro altitude?

Username Protected · **Posted:** 12 Dec 2018, 03:51

Username Protected wrote:

ADS-B reports both GPS and baro altitude.

According to this, ADS-B 1090ES actually reports the difference between GPS and baro altitudes, twice a second. Of course Mode C reports the baro altitude.

https://www.scribd.com/document/2174341 ... 1090ES-v04
Airborne Velocity Squitter data block, p. 14, last field

Username Protected · **Posted:** 13 Dec 2018, 00:39

Username Protected wrote:

Wouldn't it be easier to just use the GPS altitude and forget all about baro altitude?

No.

One, aircraft use air pressure to set flight levels. That's the meaning of flight level, flying at a set air pressure.

Two, we want aircraft to stay vertically separated if GPS is denied or fails. Air pressure never fails.

Mike C.

Username Protected · **Posted:** 15 Dec 2018, 01:01

>Air pressure never fails.
Some people on AF 447 that would not agree....

Username Protected · **Posted:** 15 Dec 2018, 10:30

Username Protected wrote:

>Air pressure never fails.
Some people on AF 447 that would not agree....

The air pressure didn't fail, the sensor did, so you can have redundant sensors.

No amount of redundant GPS receivers will save you if the GPS signal fails.

And it was pitot, not static that failed on AF447.

Mike C.

Username Protected · **Posted:** 15 Dec 2018, 19:22

Username Protected wrote:

And it was pitot, not static that failed on AF447.

It was ultimately the pilot, not the pitot.....

Andre

Username Protected · **Posted:** 15 Dec 2018, 19:41

Username Protected wrote:

And it was pitot, not static that failed on AF447.

It was ultimately the pilot, not the pitot.....

Username Protected · **Posted:** 15 Dec 2018, 20:49

Username Protected wrote:

If the pitots had worked, no accident. Blaming the pilots fully for AF447 is a travesty of justice, IMO.

Agreed, but solely blaming the pitot is naive too.

Andrew

Username Protected · **Posted:** 15 Dec 2018, 20:59

Username Protected wrote:

Both pitots failed, the computer couldn't handle it, and the pilots were given a surprise scenario they were NEVER trained for, in the black of night....the computer trimming up the stab to high AOA was a major contributor. A further problem was a stall warning that went away when the plane got slower, but came back when the plane went faster....Blaming the pilots fully for AF447 is a travesty of justice, IMO.

To some on this list, it doesn't matter. Doesn't how awful the user interface is, or the training, to them the pilot is ALWAYS at fault. Some of it appears to be a moralistic view that only humans can be at fault, never inanimate objects. But part of it may be comfort in the belief that bad things only happen to people who screw up, if you don't screw up you're immune, that you are always in control of your fate, never mind what Ernie Gann said.

Username Protected · **Posted:** 20 Dec 2018, 16:19

Username Protected wrote:

Does anyone know if the FAA has eliminated the LOA application process for ADSB equipped aircraft?

New rumor.

“The FAA is expected to publish the final rule to the August 2017 NPRM regarding ADS-B Out in Lieu of RVSM Operations tomorrow, December 21, 2018. This will amend 14 CFR Part 91, Appendix G, effective 30 days after publication on the federal register (January 20, 2018 if published on schedule), allowing appropriately equipped operators to fly domestically in US RVSM airspace without OpSpec/MSpec/LOA B046.“

Username Protected · **Posted:** 20 Dec 2018, 19:14

Username Protected wrote:

Does anyone know if the FAA has eliminated the LOA application process for ADSB equipped aircraft?

New rumor.

“The FAA is expected to publish the final rule to the August 2017 NPRM regarding ADS-B Out in Lieu of RVSM Operations tomorrow, December 21, 2018. This will amend 14 CFR Part 91, Appendix G, effective 30 days after publication on the federal register (January 20, 2018 if published on schedule), allowing appropriately equipped operators to fly domestically in US RVSM airspace without OpSpec/MSpec/LOA B046.“

Username Protected · **Posted:** 22 Dec 2018, 02:16

Username Protected wrote:

New rumor.
“The FAA is expected to publish the final rule to the August 2017 NPRM regarding ADS-B Out in Lieu of RVSM Operations tomorrow, December 21, 2018. This will amend 14 CFR Part 91, Appendix G, effective 30 days after publication on the federal register (January 20, 2018 if published on schedule), allowing appropriately equipped operators to fly domestically in US RVSM airspace without OpSpec/MSpec/LOA B046.“

They did, with no changes: https://www.govinfo.gov/content/pkg/FR- ... -27401.pdf

Username Protected · **Posted:** 22 Dec 2018, 04:04

A few days ago I was given 310 to get out of some rough weather. Never offered that before.

Username Protected · **Posted:** 22 Dec 2018, 10:58

From an email forwarded by a rVSM Jet Services in OR-
WHAT YOU NEED TO KNOW:

To enter RVSM airspace without an FAA-issued authorization, ALL of the following must be true:

Flight within the United States;
N-registered aircraft based in the US;
RVSM compliant aircraft with RVSM knowledgeable pilots;
ADS-B Out compliant aircraft (flying in airspace actively being ADS-B monitored)
ADS-B Out system must meet equipment performance requirements of 14 CFR 91.227 (Look for statement in AFM)

As far as we know, most or all other countries require "specific authorization" to enter RVSM airspace. So, to comply with ICAO Annex 6, each operator of aircraft must still apply to FAA for RVSM authorization under Appendix G, Section 3.

To fly with maintenance deferred on inoperative equipment (covered by an MEL or MMEL) each operator of aircraft must still obtain appropriate FAA-issued authorization.

RVSM and ADSB