Training and use of airborne weather radar

[Admiral346]

Wing Root,

thank you very much for pointing me to that article. It makes for some very interesting reading, and gave me a lot to try out on my next flights.

If anybody finds that video, please post...

Nic

[misd-agin]

tubby linton -

MyFCOM VOL1 states that the gain adjusts receiver sensitivity to enhance ground mapping in MAP mode only.

In FCOM Vol 2 it states that gain should always be left in automatic,unless specific display enhancement is deemed necessary.

The majority of my colleagues use manual gain outside the terminal area as the radar appears to understate the weather.

*********************************************************

Friend checking out on my equipment. Met him on the ramp. He warned about moderate to severe turbulence near top of descent.

Me - "Yeah, that's stuff been there for several days."
Him - "Our radar didn't show a thing."
Me - "What radar settings were you using?"
Him - "I started using my old a/c radar settings(manual gain/tilt settings) but the CKA(TRE) said "we don't run the radar that way".
Me - "I use the same techniques you mentioned. Your instructor flies the line twice a year. Trust me, most guys don't use the 'book' settings out here."

Caveat emptor

[Towhee]

"The Operation and Interpretation of Weather Radar,"

by Dr. Khatwa, from the 2007 Conference proceedings, is at this website:



http://www.atec.or.jp/FSF_2007_SEL.pdf

on p. 99/103


It's in Japanese; maybe someone has time to translate it.

[Towhee]

"An Analysis of the Operation and Interpretation of Weather Radar by Flight Crews,"

by Dr. Khatwa, presented at the 2007 conference, can be found at this
website:

wwwDOTatecDOTorDOTjpFORWARDSLASHfsfSPACE2007SPACEselDOTpdf


It's in Japanese, however; perhaps someone has time to translate it.

[Graybeard]

R&N Mysterious Deletions

EGMA: "Re the comments on weather radar. It shouldn't be forgotten that radar cannot see through cells. It may be that AF avoided a cell only to find a massive cell hiding behind it."
-----
The above post at about 0119z remains, yet the following reply at 0240z was deleted: why? The mods are especially aggressive at deleting weather radar discussions, but seemingly not weather reports.
-------

That statement is true of the old X-band WXR designs prior to 1982. C-band radar does not have such a limitation. C-band will penetrate heavy precipitation better than X-band, but will not detect the lightest precip seen on X-band. (Airborne C-band wx radar is 5.4 GHz, and X-band is 9.3 GHz; your microwave oven is S-band, in the 2.2 GHz range.)

UAL had always chosen C-band radar up to that time, and continued with it into the Arinc 700 era, up until about year 2000. Air France was the only other major carrier to select C-band Arinc 700 WXR, which was discontinued about the time UAL abandoned it. Only Collins produced both C band and X band WXR in that era.

Collins pioneered PAC, Path Attenuation Compensation, in the 700 WXR, which would increase the receiver gain when it sensed reduced cell penetration. When it sensed it might not be able to detect the "cell behind the cell," it displayed PAC Alert, a yellow arc on the outer range ring behind the area of high attenuation.

RCA - (bought by Honeywell) Arinc 700 WXR had the same function they coined, REACT. I don't believe Bendix/Allied Signal/Honeywell RDR-4 series ever adopted that feature, but they may have.

In short, PAC compensated for the path attenuation of X-band weather radar, making C-band WXR almost redundant.

If the WXR is not pointing at the liquid part of the storm, path attenuation is not a factor, of course.

GB

[john_tullamarine]

The mods are especially aggressive at deleting weather radar discussions, but seemingly not weather reports.

On my watch, generally only pointlessly repetitive or unacceptably aggressive etc. posts are subject to edit or deletion.

It is not my role to dictate the direction of discussion, only to keep it reasonable and somewhat pertinent to aero tech matters. As regulars would appreciate, the great bulk of Tech Log posts are fine

I suspect that your comment probably is more relevant to R&N where there has been a need to keep some semblance of order.

[Graybeard]

You're right, Mr. Tullamarine, that comment was pointed at R&N mods, not Tech Log. It troubles me that a misinformed and speculative post remains, while a factual post is deleted.

GB

[happybiker]

Dr. Khatwa from Honeywell gave his presentation on the use and misuse of weather radar at the Flight Safety Foundation Conference in Seoul in 2007. I recall it was good presentation but I cannot find a link or any notes. If any member has a contact in Honeywell perhaps Dr Khatwa could be asked to provide a copy of his notes for this forum.

[tubby linton]

A summary of the presentation appeared in the UK Flight Safety Committee magazine for Winter 2008.If you cannot find a copy on the web email them and you will be sent a copy.

[Towhee]

Dr. Khatwa's presentation

The link to the 2007 conference is already posted above, in #23.

Can you not copy and paste it into google translator?

[falconer1]

Thunderstorm Avoidance

hi folks,

do not know whether this is the right thread to post it, but coming back to square one would like to draw attention, like others have before me, to a very valuable web-site for pros and GA pilots alike..

Thunderstorms KILL!!! Get it ??!!

SmartCockpit - Airline training guides, Aviation, Operations, Safety

[falconer1]

Hi folks,

it's CB season out there...

let's get into a heated discussion about WX radars here and its use..

let's post some provocative stuff here to lure the Einsteins of the engineering departments of the radar manufacturers into this thread..

AND the flight training managers, flight standards managers, and the good folks who change boxes ( sorry repair the radars) and stumble upon radomes that are our of spec at times..

any ideas???!!!

let's roll....

[awblain]

Question on radar information

This was posted to Qantas turbulence, but is more relevant here:

Do radar users have any views about how the weather radar interface and capabilities have changed over the last 40 years, compared with other aircraft systems? Could the desire for continuity in the way the data is presented
be preventing a more readily digested weather display from being introduced?

Back in the 1960s phosphor screens and 2kb memory reasonably demand manual adjustment of the scan direction; however, the availability of electronic scanning and beamforming and heaps of processing power should surely allow a more immersive product today.

[falconer1]

I'd say

and please I would like to be challenged on that..

the design inherent deficits of inflight wx radar cannot be and have not been adressed by the new technology we have nowadays, at least not to any measurable extent..

there have been good radars 30 years ago, I fondly remember a Primus 400 in a Falcon 20 in the early 80's..(high powered cloud slicer)

nowadays I look at an also very good modern Primus WX-880 in a Falcon 900EX..(again high powered cloud slicer)

magnetron based radars in short..

In between in the 90's I have seen some, at least in my humble opinion, horrible aberrations in WX radar design, from all manufacturers , in all kinds of different birds..(mostly "low-powered flash lights" whose limitations have been further emphasized by bad quality (read that as low transmissivity) radomes..

[tubby linton]

Radar training is non existent and in my view is left up to the individual on the day to use whatever experience they may have using their own set.
I recently did a flight down the Eastern Adriatic in day time. The cells were well separated and with the radar in calibrated gain on range 120 miles it was showing only a very small green return on the route we were taking(probably only a couple of pixels).When I turned the gain to max it painted a large area of green and yellow.All I could see was high level stratus with no distinctive cummulus shape. We penetrated the area and it was a very smooth passage but at 31000ft and -43 sat we started picking up ice on the wipers for a few minutes.Before I penetrated the area I had swept the picture down to about -2 degrees to make sure there was nothing lurking in the cloud.
I was surprised at the difference between the two images that existed within one click of the gain from calibrated to max.If it had been night time and I had been in calibrated I wouldn't have seen the high level cloud and I probably wouldn't have seen the ice either until it may have had a detrimental effect on my flight.
Since the AF loss I have started to look much lower into a cloud to see what it contains and no longer use calibrated gain except at very short ranges.
Radar training has been very lapse across the industry and needs a serious reappraisal of training given to crews by the regulatory authorities.

[PEI_3721]

falconer, I agree, and I’ll add to that – the low power digitally enhanced systems, with fancy displays and modes, do little more than the old systems did except they don’t do it as well.
The modern WXRs will detect the core of a Cb much the same as the old systems, but they do little if anything to provide information about the other hazards – ice, turbulence, and lightning. We have always avoided the core of Cbs; it’s the other hazards associated with Cbs which appear to be causing recent problems – together with modern ‘delicate’ systems.

New WXRs (and some teaching / sales literature) have given many of to-day’s crews a false sense of security such that they believe that they can ‘cut the corner’ - fly closer to the storm because it is more clearly defined. The problem is that the clearer definition is at the expense of deleting (suppressing) information, whereas with appropriate guidance from training and experience, the older systems provided much better information. My training on the older systems provided basic knowledge; in-service use with help from senior pilots provided knowhow.

Another aspect is the pressure of modern operation. Although few crews admit it, and many more fail to realise, current commercial pressures do filter through to operations – even subconsciously. Add to that, the ever increasing constraints in the airspace and operating rules, then most human willpower to fly safely can be pushed to the limit – it was OK last time so we can do it again.
Much of the above is reflected in conversations – the older style “should we be doing this”, whereas the modern digital enhanced approach is “how can we do this”.
Technology does not replace airmanship: - airmanship is the difference between ‘should’ and ‘how’, and some aspects of this can and should be taught

[falconer1]

Excellent point PEI,

could well be that the fact alone that the basics of inflight weather radar have not changed and will not change in the foreseeable future, simply because there's not much more to invent here, that all this sales marketing stuff, maybe the add some more colors with the next generation, and some more REACT and other features, obscures, for some, I may add, that nothing much has changed, except that I also find some new generation "low power" models pretty useless..

and the real reason for those radars may have been that some think that the solid state stuff is cheaper to operate and maintain compared to magnetron exchanges..

magnetrons on the other hand having some finite life and having to be replaced after a certain operating time..

and that naturally is not true either, as the low power stuff also breaks frequently, and it really does not make a diff whether you pay 10 grand for a new magnetron or the same 10 grand for some ICs..

[PJ2]

The pdf file at the following site is the best presentation on radar I have ever seen with possibly the exception of Dave Gwinn's:

Honeywell's Airborne-Weather-Radar Interpretation by Ian Gilbert

[Towhee]

more on radar, fwiw

The Right Tilt

Honeywell's latest improvements to its current-generation weather radars include auto tilt to relieve pilots of having to make constant antenna adjustments to spot thunderstorms plus an upgrade to improve reliability for long-range flights.

As transport pilots know, the additional duty of constantly adjusting the radar antenna tilt is just another chore to manage. In addition, adjusting antenna tilt properly to spot storm cells and avoid frying into them requires some training and skill. The FAA has said training in the use of weather radar at airlines needs to be improved. Mistakes can and do lead to unpleasant encounters with turbulence. Avoiding such abrupt surprises will not only keep passengers and crews from injury in a high-G upset, it avoids a situation that could lead to an accident.

Some misidentified "clear air" turbulence encounters at cruise altitude actually involve thunderstorm cells bubbling up from below. Focusing the radar beam on what is happening at cruise level can totally miss these hazardous cells.

There may be very little in the way of rain to reflect the radar energy at cruise altitude, even though there could be plenty of turbulence and even hail. Hail, however, only returns 3% as much energy as raindrops. A thunderstorm below an aircraft's flight level and its true strength will be revealed best by directing the antenna beam to the freezing level where much of the rain is located, according to Stephen D. Hammack, manager of technical marketing for radar products at Honeywell Aerospace.

To make sure tilt is adjusted properly without any need for pilot involvement, Honeywell has created an auto tilt feature for its RDR-4B radar. Auto tilt can also be retrofitted onto the earlier RDR-4A model. Lance Okada, a Boeing 737-300 fleet standards captain for United Airlines, says auto tilt "reduces crew workload tremendously." The system is now certified for use on both Airbus and Boeing aircraft.

The manual technique used by most pilots is to set the radar antenna in "ground park" by lowering the beam until the display shows a little ground return at the outer edge. The radar is then set to detect thunderstorm cells. As the aircraft flies toward the cells out ahead, the thunderstorms "walk" into the beam and are picked up.

However, this technique does not work when a passenger jet is flying over water because there will be little ground return, even with high seas. "You almost have to memorize the correct tilt settings over water," Hammack says.

Tilt should also vary depending on the height of the terrain out in front of the aircraft so that ground return is minimized. For example, if an aircraft is flying into an area with flatlands off to the left of course, and mountains off to the right, the correct tilt for one would not work for the other. If the tilt is set correctly to minimize ground return over the flatlands, the antenna beam will be aimed too low for the mountains, and the display will be filled with ground clutter. And if the tilt is set to minimize ground return over the mountains, it will be too high to detect storms properly over the flatlands.

Honeywell has solved this with the auto tilt feature by dividing the 180-deg. area ahead of the aircraft into five sectors. The tilt can be varied five times during the 4-sec. sweep from left to right, for example. So each sector has the correct setting for the terrain involved based on elevations contained in the EGPWS database. The antenna sweeps at 45 deg./sec., and tilt adjustments from one sector to the next are just a few degrees at most.

Pilots typically fly at cruise with one radar set on long range (e.g., 150 naut. mi.) and the other set on short range (e.g., 30 naut. mi.). Several airlines teach pilots that once a storm is detected by auto tut, they should select manual and adjust the tilt to measure the top of the cell.
There are about 340 auto tilt systems in revenue service on Boeing 737s, 747s, 767s, 777s and the Ilyushin 11-96. This includes aircraft at United Airlines, Singapore Airlines, Japan Airlines, US Airways and Rossia, an airline in Russia. Supplemental type certificates (STCs) are also in process for the Boeing 757 and 767. Airlines pay about $6,000 per aircraft for auto tilt.

This Aviation Week & Space Technology pilot-editor saw the auto tilt function demonstrated on the Honeywell Convair 580, an aircraft that rolled off the production line right after World War II. The flight out of Boeing Field over Puget Sound was on a beautiful day, unfortunately, with nary a thunderstorm in the sky to demonstrate the auto tilt features. Seeing the Enhanced Ground Proximity Warning System (EGPWS) used in action for the first time proved quite interesting, however.

The system provides warnings well in advance of any terrain conflict by looking ahead and comparing the aircraft's flight path with a digital terrain database. The warning times are much improved over earlier generation GPWS systems. We flew to Port Angeles, Wash., and made an approach to William R. Fairchild International Airport there.

Then Honeywell test pilot Markus Johnson pointed the nose toward the high terrain of Olympic National Park where mountains rose to several thousand feet in front of us. The EGPWS map showed the elevations we had to be concerned about in red and yellow (at or above our altitude). EGPWS is designed to provide caution alerting up to a minute before a terrain conflict and to provide stronger warnings closer in.

This worked well on our approach to the high terrain with plenty of warning to pull up before closing in on the hazard. During a second pass on the same terrain, we employed the older GPWS in which there is no reference to a terrain database, just data from a radar altimeter looking straight down. When flying toward a precipice, as we were, the GPWS algorithms had little chance to spot rising terrain. The warning time was barely enough in this case, but we were VFR, and Johnson pulled up so we could head back to Boeing Field.

Another improvement that Honeywell has made to its RDR-4A and -4B weather radars is to make the antenna drive redundant. This project started out to meet the needs of Cathay Pacific Airways on its transpacific flights where radar outages have a greater chance of showing up on a long overwater leg. Previously weather radars have used a single azimuth and single elevation motor in the antenna drive, even though some aircraft such as the Airbus A340 are equipped with two receiver transmitter (R/T) units. As Honeywell notes, if either of the single antenna motors fails on the previous design, the radar is out of service.

Honeywell calculations show that if an aircraft makes 60,000 flights per year with an average duration of 5 hr. and with an azimuth motor providing 25,000 hr. mean-time-between-failure (MTBF), the airline will probably experience 19 cases of motor failure per year. These failures would cause an antenna outage and the loss of weather radar for the rest of the flight.

By installing the dual drive motors with the 25,000-hr. MTBF, Honeywell estimates there will be fewer than one antenna outage per year (0.03 per year). Since a single turnback due to loss of weather radar can be quite expensive, this $16,000 option (catalog price) can pay for itself quickly, Honeywell says.

About 200 of these dual drive upgrades have been installed on aircraft operated mostly by Cathay Pacific but also by Japan Airlines, Singapore Airlines, ANA and Rossia. While most of the supplemental type certificates so far have been for widebodies such as the Boeing 777 and 747 and the Airbus A340 and A330, an STC is in process for the narrow-body A320.

Honeywell's radar upgrade with dual antenna drive motors should cut out-ages to one per year on an aircraft
DIAGRAM: By providing two azimuth motors and two elevation motors on the antenna drive, Honeywell estimates antenna outages on an aircraft will drop to 0.03 per year.
~~~~~~~~
By David Hughes

from:
Aviation Week & Space Technology, 7/26/2004, Vol. 161 Issue 4, p47-50

[Graybeard]

Motors aren't the only thing to fail on a WXR antenna drive. Scheduled overhaul of the whole enchilada at 10K hours is a good alternative, and means less weight and less complexity.

GB