Have you read it all? If not, you should... don't take someone else's word for it, either me on an internet forum nor your local FSDO guy who also may not have read it.

It certainly doesn't read that way. Basically you can still do it the old way if you want, but the new way (section 9) doesn't require any of that - either equipment or operator approvals. It requires a certain list of equipment plus that equipment must meet a performance spec (autopilot altitude hold performance, altitude warning, plus the ASE thing that has been discussed). It does not say you have to have any specific certification of that equipment.

Where is the rule that requires aircraft certification?

Section 9 is very clear. You can fly in RVSM if you have this equipment. Period.

It doesn't say if you have this equipment which has been certified, or acceptable to the administrator.

The rule is the rule.


Quote that section for us, please.

Mike C.

Where is the rule that requires aircraft certification?

Section 9 is very clear. You can fly in RVSM if you have this equipment. Period.

It doesn't say if you have this equipment which has been certified, or acceptable to the administrator.

The rule is the rule.


Quote that section for us, please.

Mike C.

Amazing how people can read the same paragraph and come to different conclusions. You and I read that to mean the equipment requirements remain the same. Others can read the same words and come to the conclusion that as long as their altimeter is within 200 feet and their autopilot can hold altitude within 135 feet, they are good to go.

I completely understand the other side of the argument. Where they are going to run into problems is this part:



What does altimetry system error mean? It is not defined in the rule. To an operator, it primarily means accuracy of their altimeter. Anything else is insignificant and can be monitored by the FAA. To those of us who went through the training under the old rule, ASE is a combination of several items including altimeter accuracy, static system leak, static source error correction, skin waviness, and static port height. The proper equipment and inspections compensate for those factors.

It will be interesting to see how this plays out. One thing I know for certain, if you bust airspace and the feds give you a call, "Mike Ciholas said I could" is not going to get you off the hook.

Interesting that we interpret those comments differently. It is my assertion that the comment you quoted does not specify how the altimetry requirement should be met, only that it be met. You seem to believe that it means you have to keep doing the same things as before.

We are both right until an ALJ has a case and makes a ruling, probably.


Don’t mistake (intentionally) casual language on an internet chat forum for lack of understanding....

I suspect that the FAA has much more information and guidance on this topic in the hopper. Perhaps the original plan was that it be issued already and the shutdown derailed the timeline.

My interest in this topic is purely academic since my airplane is qualified and I have a LOA for RVSM ops.

The assertion is not that “it primarily means accuracy of their altimeter”.

The assertion is that the FAA, by using ADSB data and some magic computer formula they have developed, can tell in (near) real time whether you are meeting the ASE requirement, and, as a practical matter, ONLY the FAA’s magic system can really tell you what your ASE performance is (since that’s how they are defining it). And so all the certified RVSM stuff is not even the complete test anymore, the only complete test is to go fly that initial RVSM test flight and see whether your airplane passes the FAA magic system. If it does, you’re good to go. If not, then you may need some or all of that previously specified engineered equipment to meet the spec.

But the “if it works” test is simple enough and saves so much money compared to the massive pre-defined engineering route that it is worth trying.

On this "initial RVSM test flight" are you going to fly it at all RVSM altitudes and speeds that the airplane is capable of? Does different temperatures aloft change things? How about weight and angle of attack?

I do not know the answers but I bet RVSM certified aircraft have had these things tested. I know our uncorrected standby altimeter in the Ultra is usually around 300 feet high but will change with speed and altitude.

Those are specified in section 9.


Perfect. Let's check our ASE with ADS-B. Provides continuous monitoring of aircraft performance which is way safer than the old way.


That's correct, you must have the equipment in section 9. However, it provides a means to determine if you do meet the criteria.


That is correct. ADS-B *ALONE* is not enough, must have section 9 equipment *AND* actually *OPERATE* within acceptable ASE bounds.

I see not one dang thing in that paragraph that says "the FAA explicitly rejected the notion that the equipment requirement has changed." The FAA would have to have said "aircraft must still be certified under section 2". They did not say that. In fact, they went out of their way to say the opposite.

An airplane *MAY* require the expensive equipment to meet section 9 criteria *and* ASE operating limits. That's not in debate. But that equipment doesn't necessarily require the section 2 approval, and the airplane *MAY* be fine with standard equipment, particularly for the turboprops which are seeking only the low 30s and operating at low Mach numbers.

Mike C.

Most of the guidance and rule is directed to those aircraft which previously had RVSM.

Now you can drop the LOA and go operate. You can substantiate the section 9 equipment is installed (because you previously met section 2), and with ADS-B monitoring, you are good to go.

Mike C.

The way I read the rule, you can operate in RVSM as long as your ASE is monitored within bounds.

If you exceed those bounds, you get flagged.


Yes, they have been tested through a speed range, through a weight range, and through an altitude range. This is why the certification is so expensive. The data then generates a correction factor that is loaded into altimeters.

This is detailed in appendix A of this AC:

https://www.faa.gov/documentLibrary/med ... 91-85A.pdf


Jets have it much harder because they go much higher and much faster. Turboprops in the low 30s are much easier.

Mike C.

I’m having a hard time believing the Airlines, ALPA, NBAA would have not opposed the new rule if the plan was to let previously non-RVSM planes in and see what happens. Hey if someone’s off 500ft no biggie your pilots have TCAS. I always thought the point was to remove the LOA process. Still need the equipment to play.

Assuming they are 500’ off due to equipment errors and not skill/abilities, TCAS isn’t going to do jack s%$ for you as it will think you have the required 1000’ separation..

Years ago, pre RVSM, I was riding in a 441. We flew about nine hours that day. The pilot said that they had been chasing an altimeter split at altitude, but couldn’t find it. We (our employer) owned an aionics shop, so it was easy to troubleshoot. There was 1000’ error between the altimeters at FL350. The pilot was finally figuring out that the right altimeter was correct, but the mode C ran off of the left, so he was flying altitudes based on the left side. About eight hours into the flight, I stretched out and noticed his altimeter jumped. He asked that I did what I just did again, and the altimeter spun down to the cabin altitude.

Long story short, TCAS though we were right on all day when we were really 1000, off..

ATC will know because ADS-B real time monitoring detected this.

Meanwhile, the old way, a plane could have a 500 ft fault, which is surprisingly EASY to have happen, and NOT be noticed for up to 2 years.

Mike C.

ADS-B will now detect this.

Can there be any more dangerous thing than to be 1000 ft off in altitude and NOT know it? You potentially facing head on traffic at your altitude and no TCAS, ATC, mode C, panel altimeter or other system was aware of that.

Mike C.