CB / TS - during approch and landing
 

hi all

i am looking for advice on dealing with CB/TS Wx during the approch and landing phase of flight

i have tried the "net" but could not find anything useful (just theory of CB wx)

any advice and help much appreciated

fly safe

newcrew

Stay well away from them.

End of story!

What he said. Go to your alternate if necessary. Go to another alternative airport if the primary alternate is not available.

DFW and virtually everywhere in Tornado Alley - don't even
THINK about it! Either carry sufficient holding or bugger off
somewhere else.

i like that idea in theory but...

my understanding is that in some parts of the world (Africa and SE Asia) both the destination and alternate will be forcasting Sct CB (no prob or temp)

what now?

Hi,

You will have to avoid the weather using your weather radar and that's it. If there is too much of it, you may have to hold somewhere and decide to wait for improvement or divert, that means carry extra fuel. All approaches are different even with good weather so there is not a single working rule. Just use your knowledge and common sense and last but definitely not least your experience.

Cheers.

TEMP wx is also controlling for forecast destination/alternate wx, so make sure you plan appropriately. Once you get there, radar and eyeballs will be needed to keep yourself away from them. Make your divert decision early!

i guess the "problem" i have is that you may be diverting to a field which has the same (sct CB TSRA) forcast / actuals

therefore diverting from one bit of shi%^& WX to a alternate with the same!!!

not ideal to say the least...

Each operator will have their own guidance but generally it is 5-10nm horizontal separation down low and 20nm or more at altitude. On board radar is key for avoiding individual cells using the predictable and reliable precip and doppler shift returns to thread your way safely to your destination.

For terminal forecasts with 60% or greater thunderstorm coverage, additional fuel (generally 30-40 minutes) is uplifted to account for delays (ATC) or circuitous arrival paths.

Thinking that one can land in a TS is like an individual who shows up with a knife at gun fight. No good can come from it.

Remember the American Airlines MD 80 in Little Rock, AK?

That's why I said to PLAN APPROPRIATELY! If there are no distant alternatives available, and all the close alternates have the same forecast, then consider not taking off! Otherwise, look at the weather in the descent and divert to the distant alternative before you get low (You DID load the needed fuel, didn't you?).

Here's what happens :):

As Slasher says, adjust your 'extra' fuel for the weather.

It is often forgotten that the 'Div' fuel on your PLOG is from DA at destination. IF you make a sensible EARLY decision, either before TOD or soon after, you will have LOADS of fuel to reach even a far-away DIV and land with RESERVE, making INTRUDER'S logic the only sensible one if both DEST and planned DIV are rubbish.

I'm with newcrew. In my experience, it isn't the end of the story at all. If you take the tropics into consideration, there probably wouldn't be many viable airline routes in the wet season!

The way I see it, for an approach, you may well find the area covered with scattered CBs. If the airport is clear I don't see a problem with continuing the approach if you can remain clear of the weather and preferably upwind. Chances are the controller will be under a lot of pressure and you'll be vectored into the weather, so R/T traffic will be high with requests for deviations from track and late clearances can be expected. I have once heard the poor controller melt down too, obviously then you do what you have to to stay out of trouble.

I have often found CBs down the final approach track or crossing it. Quite often a change of runway is not possible or just plain refused. If faced with that you have to assess if you can parallel the track and/or get back on final before MSA and establish a stabilised approach, just be prepared to break off the approach as soon as you have doubts about achieving that and think well ahead of time in what direction you will break off to too!

Obviously the approach cannot be continued if there is TS in or around the airfield or anything where the required missed approach path will take you. Request an alternate missed approach early if necessary with consideration for how busy R/T is already.

Also, it is handy to have the confidence to be able to separate TCU from CB. TCU will be a bit bumpy but not problematic. It is also helpful to be able to differentiate radar rain returns from convective cells too. Innocent rain is flyable despite being painted red.

If you suspect that a hold maybe a good idea, try to request it early before the approach. Holding above MSA on final maybe an option too.

Keep a very sharp listen out for other traffic, keep each other informed of where the traffic is and what they are requesting, use the TCAS display with the above/below option if available.

During late final to landing, be alert for windshear, don't rely on reactive or predictive systems, but keep in mind the annunciated criteria for a windshear escape manoeuvre - its in the QRH. Obviously, with potentially challenging runway conditions a deep landing should probably be baulked.

With regards to fuel, clearly taking minimum flight plan fuel with the possibility of weather would be highly questionable. I'd probably be looking for an extra 30 mins plus, plus anything else that I usually take into consideration. Sometimes though, you have to make a decision to divert or commit, that decision needs to take into account your current position as you maybe holding away from the field significantly increasing track miles to the diversion field, so what you have entered in the FMC during preflight maybe misleading.

- but probably not - see previous post? People do forget. The Div fuel in the FMC is from DA at destination. Where you hold has little or no effect.

Sciolistes, firstly endorse your post there with much wisdom and common sense.


Going to put my hand up and plead ignorance here - how do you do that?

Cheers mate. So now I'll stick my head up. What I have seen is that convective cells paint a very distinctive picture with distinct edges and usually with clear and steep graduations from green to a red centre (usually offset). The cells can be conjoined but they are still clearly cells. Just rain from cu strat or what I presume are the remnants of CBs with no significant convection; this all looks like a nebulous mass with indistinct edges, sometimes green with indistinct splodges of yellow and red within or sometimes just a mass of nebulous red. For sure, you have to be careful using gain and tilt to ensure you are getting the fullest picture.

BOAC,
Point taken. All I can say is that I have unthinkingly come up with an divert time after reciting the prog and perf pages without thinking spatially. Likewise, I have picked the Capt up on it too. By extension I figured it is an easy and dumb mistake to make.

FFB - the only caveat I would place on 'assessing' rain as opposed to a CB is to, as SC rightly says, use the tilt carefully. Just when you think it is 'OK ' to go through that red/green 'splodge' because it is rain, beware, and think where that rain comes from. Known always (well, nearly always) to travel downwards, remember the old advice of being careful if you fly UNDER a CB.

Looking at the radar 'contour' is normally reliable as stated.

hi all

thanks for the reply's so far

what i was taught was never over / thru / under - your comments!

any minimim lateral avoidance if downwind of CB below 5000 agl?

fly safe

Clearly the "stay well away" strategy is optional in Cuba! Can anyone give an opinion on this landing? It looks nasty but at the same time there is little wind or turbulence.

There is an expression for this sort of behaviour.

"RUSSIAN ROULETTE" :rolleyes:

Yeah I agree, there is no real way of knowing what winds you are going to get in that last few hundred feet and they could be pretty extreme changes. Also, you don't know if the runway is going to be contaminated with standing water, so if you get some nasty shear at low level and try to land it on standing water....bad news, if you get same and go around you could end up climbing out into more bad news. It's leaving no good alternative if things don't go your way.

… and what thoughts about braking action if you do get on the runway. Flooded surface, considerably more distance required; possible crosswind … lower crosswind limits.

The initial approach scene looks as described in this event: Windshear Incident

My thoughts are aligned with yours by the sounds of things.
I have to admit that as a 737 f/o I flew an approach and landing very similar to this. It was a check flight with a check pilot in the middle seat. It went without incident but I've always been a bit dissapointed with myself for not explicitly stating my wish to take a heading and hold. The authority of the two I was with was such that I allowed it to override my own judgement. That said, I am happy that I have progressed enough over the years to feel like I wouldn't do it again.

Re the video. Quite an astonishing decision to land. Especially as the conditions are improving. But what about the Airbus reporting 800 meters. That'll be the rain directly underneath the cell!

Framer,
I am sure most of us have been there. But I think that sometimes we need these experieces, without them we risk slipping into a meek attitude when it really matters.

Thunderstorms!
 

one crew:

Hold away, if you have the fuel until the weather improves, or off to your alternate.

From long experience with South East Asian Thunderstorms, a rough guide {and it is only rough}is that many storms follow the 30 minute guide, 30 minutes building, 30 minutes at full force and 30 minutes dissipating. The trick is to know which 30 minute cycle it is in when you arrive!.

How many times have we all arrived in less than pleasant circumstances, only to find that a little while later, the sun or moon is out and visible.

Tmb

Tmb is on the money. Those full force buggers can be bloody
dangerous below 500ft while the dissipating ones look nasty
but are just lots of heavy rain with the odd thunderbolt, and
not much else.

If a cell lies ON the approach (but of sufficient distance away
from the MaPt) I delay gear and landing flap to cater for any
potential d/drought or m/burst or e/failure (esp if in a level
flight component) and enough performance fat for a possible
GA due to same.

Good indicator I've found (assuming you're in wx conditions
permissable to see it and allowing for the position of the Sun)
is the colour of the rain. If its dark blue be very careful, and if
its BLACK you don't go anywhere within a bull's roar of it - TO
& TO path, APP or LDG, or even GA!

If your radar goes up the **** (and it happened to me a few
times when I was in Nam during the Wet) get as much info
as you can, as well as visual observations if you're lucky to
break free of cloud on descent for a few secs. Get the FO to
monitor Tower for any missed apps. If there are any then it
might be good to plan to hold somewhere till no further MAs
occur.

Do respect that W/SHEAR AHEAD noise if you're fitted with
it. When its working properly it is quite accurate.

As for that F70 approach - from 1000ft down to the deck I'd
be looking for the first excuse to GA. Other words I keep the
mindset "I'm going to GA" unless each condition from second
to second continues to prove its safe to keep going - and I'm
talking right down to the deck, not just to the published min.
I'd also be bitching to the Tower for its instant wind readout
every 100ft from 500ft AGL down.

I mentioned in a prev post about Tornado Alley.As for Europe
and Central China (and probably good for all areas outside of
Tropic lats) best to just stay away till it clears.What looks like
a pissy 30,000 footer over LHR is like a humungous 60,000ft
thumper over Singapore. Boyle's (or is it Charles?) Law and
all that.

As Framer said, Go around to where? That crew pretty painted themselves into a corner, if they couldn't land they would have had to put themselves in the thick of it.

You have to read what the actual clouds are telling you Sci -
it comes with experience in tropical lats. I wasn't there but
the cells on that vid appeared to me as moderate. Any GA
would've been rough but a near 180 asap would've already
been organised with ATC by the crew (again I wasn't there,
just as I don't know whether the FO's radar was set to level
8 on Multiscan or CAL in Manual).

BTW it just occured to me - what's an F70 FO doing with a
bloody vidcam on a critical app?

F100 video into Havana
 

My windscreen rain-o-meter coupled with the lack of bumps on the way in suggests a lucky just-in-time arrival and much less troubling than what was painted on the ND. Also, it was not the worst of possible gradients one might see in the wild.

The real cowboy question would have been where to in the case of a MA?

well, like stated above just make sure not to touch down in a squall with all the funny windshear and heavy gusting winds or go straight through a CB on final and thats it.

its always a good idea to check if you expect some ocnl cb,s or a wall of them at destination. thunderstorms in the area are a non event when you can navigate around them.

Carry extra fuel, then hold away from WX and wait till the first captain of another airplane requests diversion, then request diversion yourself.

Slasher,
The way I read it, the Airbus reported 800m vis, the controller reported +TS. The 800m vis is a typical tropical CB unloading. The weather radar had a completely inappropriate tilt of +1, showing ground returns and would not have shown the cells properly.

Living as a pilot in a country that has >3500mm of annual rainfall and afternoon TS as frequent as 200 days per year, I would say only experience can teach you how to deal with it.

As you asked for approach and landing phase, I will share my thoughts on just that.

1) Check out the CB cloud like the way you check out the women if you can see it. Top, middle and how her skirt(curtain of rain) flares. How tall the top tells you how much vertical activities inside. How wide the middle portion tells you how much juice it has inside. How the skirt flares tell you the TS is in which stage. Straight skirt say just started,microburst is around the corner. Flare skirt says windshear/micoburst may be happening.

2) Stages of the TS tells you wind direction. Example: you're 10nm final on ILS, a TS 3nm at the runway 2 o'clock would be sucking up sh!t until it bust. Once burst, it give you a strong headwind on short final. Best to compare your spot wind at glideslope capture and tower wind. This comparison prepares you for any wind direction shift(nose cock) and wind speed change prepares for possible airspeed lost.

3) ALWAYS-go thru missed approach drills on final and commander should let you know he is ok if you elect to go-around. So, you will not feel pressured to land.

4) Good to check fuel quantity prior intercepting ILS. Alternate airport weather should have been obtained prior if fuel is not the luxury.

5) ALWAYS- Visual with runway does not mean you must land. Beware of last minute unstabilised apporach

6) ALWAYS- Water on runway takes about 15mins to drain out if runway NOT grooved. Don't rush for approach once visibility improves.

7) If runway surface is undulating, it can have multiple patches of water, antiskid can work against you. Use the reverser until taxy speed.

8) Lastly, no one likes aircraft on mud and wet grass, especially management!

LOOK at the clouds in that vid Sci, look for the roll cloud and
count the flashes. Also count the number of observable TS
cells. Which way are they moving? Approaching the airport or
moving away or sideways?

A dissipating bunch of cells can have 800M just as building
cells do. Same with very heavy showers.

I couldn't see what the tilt was (thanks), which explains why
the FO's radar display was so completely different to direct
observation. A mate of mine once told me "One look outside
is worth a thousand radar returns."

There's just so much information missing from that vid that I
never said the crew were right or wrong. They may have org-
anised a 180* missed app or they might not.

Anyway that's all I'll say. I've posted far too much above my
normal amount for a TL thread already.

PS - ditto what the poster above just said.

any minimim lateral avoidance if downwind of CB below 5000 agl?
 

hi all

thanks for the reply's so far

what i was taught was never over / thru / under - your comments!

any minimim lateral avoidance if downwind of CB below 5000 agl?

fly safe

any minimim lateral avoidance if downwind of CB below 5000 agl?
 

hi all

thanks for the reply's so far

any minimim lateral avoidance if downwind of CB below 5000 agl?

fly safe

While I don't necessarily see a problem landing with CBs in the area in the tropics, and I do agree that doing it in tornado alley (the Midwest or over any set of high plains) is foolish, I think that too much advice is directed in the "don't ever do it direction".

Unfortunately, that sort of advice does someone little good when they arrive over an island with an alternate (and only other airport you can reach) several hundred NM away and minimal fuel. The advice given by Sciolistes is spot on. The rain shower in the video was moderate at best.

Proper usage of radar is hardly ever taught and using the radar to "read" the cell at various levels is something that has gone by the wayside, instead I see many turn the gain to max and point it at 0 degrees, this is probably the 4th most useless thing in aviation.

Now, I'm not a tremendous fan of Airbus, but they have put together a rather good briefing on how to use radar to your advantage.

Remember that the wx-radar display will become quite dramatic the closer you are to the cells/rain. Before you know it everything is painted red. So it helps a lot to have a clear picture of the approach path 30 miles before you enter the area. This will usually nicely show the difference between 'just stratus' and thunderstorm cells.

Well, here we go again...
 

Well, here we go again...

What is your company's SOP regarding this topic?



Fly safe,


PantLoad