We had radar Altimeters in some of the birds long ago for low level, under 1000ft flying. I would hope they are standard equipment in modern military aircraft like a blackhawk or a commercial aircraft for low altitude for takeoffs and landing.
https://www.precisionhelisupport.com/faa-stc-sr02586la-radar-altimeter/
I remember 5G causing possible issues with them.
https://www.faa.gov/air_traffic/publications/domesticnotices/dom23021_gen.html

I'm not saying it's a problem here, only that they are commonly used today.

 

We had radar Altimeters in some of the birds long ago for low level, under 1000ft flying. I would hope they are standard equipment in modern military aircraft like a blackhawk or a commercial aircraft at low altitude for takeoffs and landing.

I remember 5G causing possible issues with them.

Radar altimeters give you altitude above the ground, which is NOT what you want for aircraft separation.

What you need is something that ALL aircraft operating in the area have such that if two aircraft in close proximity indicate the same altitude, then they actually are at the same altitude as each other (within the tolerances of the equipment). It doesn't matter if the altitude they think they are at bears any resemblance to their true altitude. This is why all aircraft operating above 18,000 ft MSL set their altimeters to 29.92 and report their altitudes as "flight levels". Close to the ground, you want your altimeter to read very close to the true altitude (above mean sea level, MSL), because you need to be aware of your altitude relative to terrain and obstructions on the ground. It's also important that your altimeter agree with the ground when taking off and, especially, when landing. But even a correctly set altimeter is usually only correct (i.e., indicated altitude equals true altitude) on the ground (and at the point where the altimeter setting was determined -- usually by adjusting an altimeter so that it reads the correct elevation at that spot). Above it (or below it if you, for instance, take off from an airport on a plateau and then fly into a valley), the altimeter bases its indication on the standard atmosphere with just that one adjustment. It doesn't adjust for temperature, for instance. Also, the physical atmosphere is pretty much guaranteed to not follow the standard model at any particular time. So the indicated altitude can be off by quite a bit as you get several thousand feet above the ground and further away from the point at which the altimeter setting was determined. But that's okay, because aircraft will still have proper separation as long as they do so based on the same altimeter settings.

 

Radar altimeters give you altitude above the ground, which is NOT what you want for aircraft separation.

What you need is something that ALL aircraft operating in the area have such that if two aircraft in close proximity indicate the same altitude, then they actually are at the same altitude as each other (within the tolerances of the equipment). It doesn't matter if the altitude they think they are at bears any resemblance to their true altitude. This is why all aircraft operating above 18,000 ft MSL set their altimeters to 29.92 and report their altitudes as "flight levels". Close to the ground, you want your altimeter to read very close to the true altitude (above mean sea level, MSL), because you need to be aware of your altitude relative to terrain and obstructions on the ground. It's also important that your altimeter agree with the ground when taking off and, especially, when landing. But even a correctly set altimeter is usually only correct (i.e., indicated altitude equals true altitude) on the ground (and at the point where the altimeter setting was determined -- usually by adjusting an altimeter so that it reads the correct elevation at that spot). Above it (or below it if you, for instance, take off from an airport on a plateau and then fly into a valley), the altimeter bases its indication on the standard atmosphere with just that one adjustment. It doesn't adjust for temperature, for instance. Also, the physical atmosphere is pretty much guaranteed to not follow the standard model at any particular time. So the indicated altitude can be off by quite a bit as you get several thousand feet above the ground and further away from the point at which the altimeter setting was determined. But that's okay, because aircraft will still have proper separation as long as they do so based on the same altimeter settings.

But I this case it seems, altitude above ground is a critical factor to look at more that pure separation because both were so low to the ground. For a helo it's nearly always critical to be precise by some method.

https://xcmag.com/news/gps-versus-barometric-altitude-the-definitive-answer/
Reading this makes me understand our post about the issues.

 

But I this case it seems, altitude above ground is a critical factor to look at more that pure separation because both were so low to the ground. For a helo it's nearly always critical to be precise.

I didn't say it wasn't a critical factor. If an aircraft has equipment to determine height above ground, great. They should definitely be monitoring it when close to the ground.

But that is a completely separate and unrelated issue to what is involved here. The issue here is whether they were violating the 200' MSL ceiling (assuming I caught that information correctly on that chart), which has nothing to do with height above ground. Aircraft altitude clearances and restrictions are based on indicated altitude according to an altimeter using the current setting -- that is a common piece of equipment that all aircraft operating in controlled airspace are required to have. Transponders, on the other hand, report pressure altitude (i.e., the altitude that would be indicated if the altimeter were set to 29.92" Hg). ATC radar displays (at least used to, things may have changed given the advent of things like ADS-B and the like) display aircraft altitudes based on the data received from a transponder operating in Mode-C, which means that it is altitude-encoding. Any aircraft operating below 10,000' MSL and within 30 NM of a Class B airport is required to have an operating Mode-C transponder (this is known as the "Mode-C veil"). The transponder reports pressure altitude in 100' increments, so the fact that the radar display shows 300' PA isn't a very good indicator of whether or not the helo was violating the 200' MSL indicated ceiling.

 

I didn't say it wasn't a critical factor. If an aircraft has equipment to determine height above ground, great. They should definitely be monitoring it when close to the ground.

But that is a completely separate and unrelated issue to what is involved here. The issue here is whether they were violating the 200' MSL ceiling (assuming I caught that information correctly on that chart), which has nothing to do with height above ground. Aircraft altitude clearances and restrictions are based on indicated altitude according to an altimeter using the current setting -- that is a common piece of equipment that all aircraft operating in controlled airspace are required to have. Transponders, on the other hand, report pressure altitude (i.e., the altitude that would be indicated if the altimeter were set to 29.92" Hg). ATC radar displays (at least used to, things may have changed given the advent of things like ADS-B and the like) display aircraft altitudes based on the data received from a transponder operating in Mode-C, which means that it is altitude-encoding. Any aircraft operating below 10,000' MSL and within 30 NM of a Class B airport is required to have an operating Mode-C transponder (this is known as the "Mode-C veil"). The transponder reports pressure altitude in 100' increments, so the fact that the radar display shows 300' PA isn't a very good indicator of whether or not the helo was violating the 200' MSL indicated ceiling.

As a non pilot:
I would trust the ground landing system data on this and other jets making the same approach as the standard to judge a violation by proxy. The reason for 200 msl is assumed by me as being where a plane during landing should never be over the helo route crossing the airport.

 

I suspect this is related to DJT's comments yesterday:

 

https://www.msn.com/en-us/news/othe...ly-pose-dangers-to-passenger-jets/ar-AA1y9jMR

 

And with the current explosion of drones, and the imminent arrival of personal flying vehicles, things are about to get much more crowded. It's only a matter of time before said vehicles are required to automatically self-coordinate. Things are about to get much more interesting in the following decade.

 

And with the current explosion of drones, and the imminent arrival of personal flying vehicles, things are about to get much more crowded. It's only a matter of time before said vehicles are required to automatically self-coordinate. Things are about to get much more interesting in the following decade.

It will help to have competent people running things.

 

It will help to have competent people running things.

People are always the key to a good system ... and also its main weakness.

 

Wake Up!

 

Wake Up!

Years of Victory: 50 0

 

https://www.msn.com/en-us/news/othe...ly-pose-dangers-to-passenger-jets/ar-AA1y9jMR

 

Heads had better roll. I'm thinking a criminal investigation now. Lives were lost.

Someone had overall responsibility for the safety of this airspace. And that person also had a supervisor.

 

Heads had better roll. I'm thinking a criminal investigation now. Lives were lost.

Someone had overall responsibility for the safety of this airspace. And that person also had a supervisor.

The essential question here is why the helicopter climbed above the maximum permitted height IMO. That video shows them (the helo) bouncing up/down causing CA/RA alarms with approaching aircraft. The ATC seems to be minor slice of the swiss here.

 

 

The headline on the bottom of the screen when I first saw this report said, "Air Force F-35 suffers major damage." Had to laugh at that one! It should have added, "May not be repairable."

 

The headline on the bottom of the screen when I first saw this report said, "Air Force F-35 suffers major damage." Had to laugh at that one! It should have added, "May not be repairable."

That zero zero seat is a life saving wonder. The plane was non-flying brick a punchout.

A zero-zero activation of the seat.

 

Portland Police say TriMet bus driver Mike Perrault was hijacked by gunman Hosea Chambers during a terrifying ride through Old Town on Wednesday, Jan. 29. 2025. Dispatch audio captured part of the ordeal before Perrault allegedly disarmed Chambers and fled the bus.

 

How could you miss that airplane flying across your helo flight path? The Blackhawk pilot had assumed responsibility for avoiding all aircraft from the ATC at that point while crossing under the landing path.