Hello,
As a “young” IFR pilot (350h TT), I would like that elder pilots, including airline pilots (plenty there !), could explain their strategies dealing with the weather in the terminal aera.
Obviously, we have different sources of informations:
*Datalink: with anticipation, it can shows us a cell above the airport or on the approach, and the movement of the cell.
Had that sometime, and decided to slow down as much as I could, so that the cell could have gone when I would arrive.
I would like we could discuss the different means, and the strategy to start the approach: when (IAF ?), on what conditions, when to abort (except minimas !!)
Well, I’m no airline pilot (but Bizjet) and over 50, so “elder” might apply 
Regarding your points:
- Visual: What you can see with your own eyes is always the best information. Sometimes an early or late descent/climb is a good stategy to keep the nasty stuff in view. Especially during summer, when the cloudbases are high (4000ft to 5000ft) an early descent below the base can be good for ones’s peace of mind.
- METAR – and even more up-to-date: ATIS! A good source of information, but really only for the airport itself. Something like “showers in the vicinity (VCSH or VCTS)” doesn’t help much apart from keeping you awake. Monitor ATIS frequently, in stormy weather there are often “specials” outside the usual 30-minute sequence.
- Stormscope: A very good tool, especially in combination with a weather radar, because it lets you discriminate between rain clouds and real thunderstorms. Unfortunately, very few transport category aircraft are equipped with it.
- Onboard weather radar: A absolute must for commercial all-weather operations. Flying privately, you can always decide to stay on the ground when there are actual of forecast thunderstorms in the region. But in commercial operations, you have to fly in every weather, and therefore the Radar is a vital item. However, interpretation of weather radar images is more an art than a science and needs to be practised for a long time (one of the reasons why you need 1500 flying hours before you get the full ATPL and can fly transport category aircraft in command).
How to use it? Keep it in standby mode all the time when flying IFR, just like you turn on your pitot heat all the time. Whenever convective clouds can be seen or anticipated, turn it on. It is there to be used. “Saving” the weather radar by using it as little as possible is one of the most stupid things a pilot can do. That might have been a valid point 30 years ago when these things had vacuum tubes that only lasted for a certain number of hours. But now they are all solid state, the latest ones completely without moving parts using electronically steered antenna beams, and last as long as any other avionics item.
The earlier you turn it on, the more time you have to develop a strategy. From my experience, the best range is 20-50NM, so have it on before the distance to the first clouds gets below 50NM.
What to do on a STAR and in the ILS? On SIDs and STARs it is often possible to deviate for avoidance unless there is terrain close by. Usually ATC is very helpful and grants every request. In thundery weather, the distances between departing and arriving aircraft are increased to enable some manuevering. This is why at larger airports you will often get a slot in summer with “WX” given as reason (“REGCAUSE”). Sometimes on departure, when there are buildups right on the extended centreline a couple miles ahead, an early turn can be requested while still on the ground.
When you are already on the ILS and something is moving in your path, go around immediately and request vectors around it. I have seen plenty of aircraft that looked like those 1930ies corrugated-aluminium Junkers planes after flying through a hailstorm on final. Totally unnecessary and for many employers a reason to terminate your work contract on the spot. Leave your radar on until safely on the ground. Even if your approach path looks free of storm clouds, you always might have to go around, e.g. due to windshear caused by squalls from a CB. Turning on the radar while already in the go-around might be too late. When approaching in stormy weather always consider the situation you are going to face in an eventual go-around. If you can see that the standard missed approach path is blocked by red dots on your radar, tell ATC what your intentions in case of a go-around will be so that they can keep the sky clear for you.
-Datalink: I have no experience with that, but due to the obvious time delay between measurement, transmitting and displaying the data in combination with a very limited resolution this can not be a true replacement for on-board equipment. An additional source of data and a backup maybe, but not more.
When I flew IFR in the AA5 in convective weather, I used a combination of visual avoidance and the storm scope, which were the only real time tools I had. Embedded thunderstorms were a good reason not to go flying that day.
As what next says, a weather radar is a requirement for proper terminal avoidance. As an aside, I’m interested to see you keep your radar on Standby unless you need it – I have encountered this a lot since I started flying bizjets and I don’t quite get why you wouldn’t be transmitting the whole time?
I have encountered this a lot since I started flying bizjets and I don’t quite get why you wouldn’t be transmitting the whole time?
Two reasons: If you leave the radar on all the time it tends to clutter the navigation display (which is very low resolution by modern standards in our aircraft) and slows down the display updating considerably.
And then, our younger co-pilots (who have no children yet) are scared of getting their DNA damaged by reflected microwave energy so we try to keep their level of exposure as low as possible.
Also radar completely wipes out the stormscope of any nearby aircraft.
It may even damage avionics if you are close enough e.g. on the ground. I had the GS input mysteriously blown up on both NAV radios recently.
As to the OP, it appears to ask about approaches rather than departures.
With an approach, one is normally high up (VMC on top) so you can see what is generally around. If the cloud tops are smooth, there isn’t going to be a TCU or a CB in there, so a descent into it is OK.
Then it comes down to the chances of icing. I usually find that the temp inside a cloud is 3C below the air immediately outside, so if just above is 0C you can be assured of icing inside – especially as the tops are the wettest part. So you have to go for a rapid descent strategy. At some airports you can get a hold (rare for piston GA but I got one at Zurich) and that can screw you up, so in that case it’s better to tell ATC you will want a continuous descent due to icing conditions below.
Departures are much more tricky because usually you can’t gauge how high the tops are, visually.
We normally switch the Radar on when lining up and off on vacating the runway. Interesting to hear about computer problems on older avionics. I would however be very surprised if a certified unit had issues with radiation sat directly behind the transmitter. I thought side lobes from that type of array didn’t appear more than 90° from the intended direction of transmission?
Regarding visual weather avoidance in the cruise, this is the kind of thing I’m talking about (taken at FL100 on a heading to avoid):
Two reasons: If you leave the radar on all the time it tends to clutter the navigation display (which is very low resolution by modern standards in our aircraft) and slows down the display updating considerably.
Doesn’t it also “wear out” the radar antenna? I thought I read something like that in the pilot’s guide to a P210 radar.
“I would like we could discuss the different means, and the strategy to start the approach”
I am only a private pilot with a SE-Cessna-airplane equipped with a stormscope, no on board radar, no data link.
A couple of years ago I was approaching Riga-EVRA coming from Germany. The weather forecast was pretty good for the flight, otherwise I would not have departed.
Some 50 miles west of my destination I could see many buildups in the terminal area which have not been predicted. ATIS reported TCUs with showers in the vicinity.
While coming closer to the IAF I realized some nasty dark clouds just on my way to the ILS. At that point I decided to cancel IFR and proceeded at 1500 ft safe below the stuff.
This strategy is easy and an advantage of small GA planes as a plan B with no terrain on the way and a ceiling high enough.
While coming closer to the IAF I realized some nasty dark clouds just on my way to the ILS. At that point I decided to cancel IFR and proceeded at 1500 ft safe below the stuff.
I had a similar situation in Krakow under VFR. There were widespread thunderstorms (not forecast) in the terminal area. The airport refused landing clearance because it had an airliner sitting on the runway waiting for the thunderstorms to move and takeoff. They insisted on this airliner taking off first and my hovering around the thunderstorms. I had to declare an emergency until they sent the airliner off the runway. It was rather early in my flying career and very scary.
Last year I did a comparison of the usual weather avoidance tools with many pictures:
http://www.ing-golze.de/blog_marem.jsp
But that was enroute. If there are cell on the ILS I will fly to the alternate, slow down in cruise, hold until the weather is gone or appraoch from the other side if possible. If you really want to avoid a CB which is on the ILS you either have to see it visually or have on board radar. But even then you might just avoid the core and the approach might be very unpleasant. So even though we also have on board radar I would leave that to the bigger planes.
