AFGMEL
Topic Author
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Take Off In Fog

Fri Sep 18, 2009 12:30 am

Didn't want to hijack this thread about landing in fog.

A few years ago, we were flying out of MXP with MK on an A343 and the fog was so dense you couldn't see the terminal from the aircraft. Just a blur of lights. The taxi was endless and eventually we waited and I saw what I thought was a "follow me" truck and then we carried on taxiing. I doubted that we were going to depart and I presumed we had got lost.

We did depart however. I wondered about that departure because I doubted we could easily have returned in was looked like cat IIIC conditions, but I am not an expert. What if we had to return? Presumably the pilots thought it was safe which is good enough for me.
B 727-44/200 732/3/4/8/9 767-3 742/3/4, 772/3, A319/20/21 332/333 342/3 , DC3/4/10, F28/50/100, ATR72
 
sandrozrh
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RE: Take Off In Fog

Fri Sep 18, 2009 12:36 am

Quoting AFGMEL (Thread starter):
We did depart however. I wondered about that departure because I doubted we could easily have returned in was looked like cat IIIC conditions, but I am not an expert. What if we had to return? Presumably the pilots thought it was safe which is good enough for me.

That is why during low visibility conditions (if we're not legally able to return to our departure aerodrome due weather conditions, landing capability restrictions etc.) as you may have had on this day, we need to plan a take-off alternate with weather conditions sufficiently well for whatever approach we want to do there (plus certain "safety margins" in addition, i'm not going into detail here because I'm too lazy to explain  )

So if for whatever reason we'd need to turn back, we'll simply proceed to our take-off alternate aerodrome instead of returning to the departure aerodrome. (well its not that easy really, but that's the general idea).

Hope this helps.

[Edited 2009-09-17 17:42:24]
 
GXMan
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RE: Take Off In Fog

Fri Sep 18, 2009 12:36 am

I cannot comment on MXP, but on numerous flights at SFO we take off and land in what appears to be zero visibility. Many times I thought we were in the clouds and then bam! The landing gear hits the runway.

I guess technically we were in the clouds, the clouds were just on the ground.
Steve
 
OPNLguy
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RE: Take Off In Fog

Fri Sep 18, 2009 12:45 am



Quoting AFGMEL (Thread starter):
What if we had to return?

I can't speak for the regulatory set-up outside the USA, but here there's a reg that if the departure airport is below landing minimums but above takeoff minimums, the dispatcher must designate a takeoff alternate that meets the weather requirements for an alternate. The takeoff alternate can't be any more than 2 hrs flying time from the departure airport (for a 3- or 4-engined aircraft) or 1 hr flying time (for a twin-engined aircraft). This gives a departing aircraft someplace to land in the rare event they have a problem that necessitates a return.

I presume regs in other countries have something similar in place...
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
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DocLightning
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RE: Take Off In Fog

Fri Sep 18, 2009 12:52 am



Quoting Gxman (Reply 2):
I cannot comment on MXP, but on numerous flights at SFO we take off and land in what appears to be zero visibility.

at SFO you have OAK 3 miles away and SJC about 20 miles south (admittedly, not along either SFO departure track).

Also, the fog at SFO is interesting. North of the airport, you have what is essentially a perfectly predictable fog bank. It is always there during the summer and moves south towards the airport at about 3-4 PM.

It rarely covers the airport, but when it does, it is guaranteed to clear 1-2 miles south of the airport. And fog in SF starts and ends abruptly. Like, from one end of a city block to the other. So although it might look like pea soup on the ground, just 300 meters away, people might be standing in broad daylight marveling at a giant fog bank blowing past them and you'd never know it.

Definitely get an areal tour of SF if you ever visit.
-Doc Lightning-

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cobra27
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RE: Take Off In Fog

Fri Sep 18, 2009 5:56 am

Are there any specifical takeoff minums?
I think in US you can takeoff in zero visibility, but I find a little strange? Did anybody do it?
Takeoff with seeing the centerline?
 
brains
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RE: Take Off In Fog

Fri Sep 18, 2009 6:21 am

There are standard t/o minimums per the FARs in the US. Standard T/O mins for a two engined aircraft is a visibility of 1 SM. 1/2 SM for an a/c with three or more engines (if I remember correctly from school). However rarely do scheduled operators use these standard T/O mins. More often than not their opspecs allow them to take off with substantially lower visibilities. In fact they are RVRs so low that there really is no comperable equivalent in statute miles. My airlines is authorized to depart with RVR 600ft, 600ft, 600ft and RVR 600ft, 600ft assuming runway centerline markings are in good condition and runway centerline lights are operative. High intensity runway lights are also required (without HIRL you cannot get RVR) At least two RVR transmissometers must also be operative. I believe DEN authorizes takeoff with even lower RVR, but dont quote me. I fyou have access to jeppesen charts, lido charts etc. you'll be able to find T/O mins for individual runways in the airport information pages.
Brains
 
wilco737
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RE: Take Off In Fog

Fri Sep 18, 2009 6:54 am



Quoting Cobra27 (Reply 5):
Are there any specifical takeoff minums?
I think in US you can takeoff in zero visibility, but I find a little strange? Did anybody do it?
Takeoff with seeing the centerline?

Every airport published the applicaple minimum for their own airport. This is the lowest minimum weather possible. if the airplane or cannot reach that minimum, they take their own, higher minimum and then they know if they can take off or not.
I don't have my charts at hand, only one from BOG and the lowest permissible minimum for take off is 350m. But then the whole lighting system of the runway needs to be operational. Edge lights, centerline lights, touchdown zone lights, red centerline lights at the end, runway end lights etc etc...
In FRA even 125m is possible. So if you have 125m RVR for take off you can take off (if your airplane and crew is certified for it). But that means that you usally cannot land anymore. So you need a take off alternate.

wilco737
 
CosmicCruiser
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RE: Take Off In Fog

Fri Sep 18, 2009 1:19 pm

Also keep in mind that this T/O min is only for the RVR for a given runway. The prevailing vis anywhere else on the airport may be better or worse. The RVR is controlling.
 
AAR90
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RE: Take Off In Fog

Fri Sep 18, 2009 2:44 pm



Quoting Cobra27 (Reply 5):
Are there any specifical takeoff minums?
I think in US you can takeoff in zero visibility, but I find a little strange? Did anybody do it?
Takeoff with seeing the centerline?

As with landing runway minimums, there are takeoff minimums for each runway as well. Lowest visibility AA 738s are permitted to takeoff is 300' (75m)... IF the runway is rated to 300'. We regularly train to 300' vis in the simulators. Definitely a "tunnel vision" scenario.

AFAIK, the only "zero vis" takeoffs permitted in USA are military flights... and only if the pilot has a "special instrument" rating --that's a USN requirement, USAF probably has something very similar. I have done two (both at KNKX). Not fun!
*NO CARRIER* -- A Naval Aviator's worst nightmare!
 
DashTrash
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RE: Take Off In Fog

Fri Sep 18, 2009 2:56 pm



Quoting AAR90 (Reply 9):
AFAIK, the only "zero vis" takeoffs permitted in USA are military flights

Zero viz takeoffs are legal under Part 91. Not the smartest thing to do, but still legal.
 
CosmicCruiser
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RE: Take Off In Fog

Fri Sep 18, 2009 4:42 pm



Quoting DashTrash (Reply 10):
Not the smartest thing to do, but still legal.

You got that right. Some peoplre every year find out they can't do a 0 vis T/O or fly IFR when they aren't rated.
 
meristem
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Joined: Wed Jun 03, 2009 4:50 pm

RE: Take Off In Fog

Fri Sep 18, 2009 5:12 pm



Quoting DocLightning (Reply 4):
It rarely covers the airport, but when it does, it is guaranteed to clear 1-2 miles south of the airport. And fog in SF starts and ends abruptly. Like, from one end of a city block to the other. So although it might look like pea soup on the ground, just 300 meters away, people might be standing in broad daylight marveling at a giant fog bank blowing past them and you'd never know it.

I live in that dratted fog line.
SFO is protected from fog by the Twin Peaks barrier within San Fran proper and smacked by the San Bruno and Golden Gate fog corridors.
Most of the fog behaviour is due to the interplay of maritime influence and the higher temp/lower pressures inland in the Sacramento delta and central CA. On and off you'll have fog covering the bay via the delta but that's thin in comparison.
Visitors are often shocked at the generally low temperature and lack of sunlight within the fog corridors (Golden Gate Bridge, San Bruno, San Mateo Gap) during summer. The fog speed and profile is very much like a cresting wave. If you visit in Jun-Aug, bring a fleece jacket (seriously).
As DocLighting mentioned, the fog line is so sharp and sudden that it is a common Real Estate topic of conversation ("Buy in street X between 23rd and 24th streets, stay away from 26th, and there is one block on 25th where the sun shines")
After a while, one gets versed on "high fog", "low fog", "tule fog" and other different fog proclivities based on time of year.
Curiosity killed that cat. I still have some lives left.
 
corey07850
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RE: Take Off In Fog

Fri Sep 18, 2009 9:14 pm



Quoting DashTrash (Reply 10):
Zero viz takeoffs are legal under Part 91. Not the smartest thing to do, but still legal.

Yep, completely stupid. Many moons ago during my instrument training I had an instructor that would practice 0 vis takeoffs... basically you get the plane on centerline, put the hood on, then maintain runway heading using the DG. Glad when those were over
 
pilotpip
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RE: Take Off In Fog

Sat Sep 19, 2009 2:49 am



Quoting Corey07850 (Reply 13):
Yep, completely stupid. Many moons ago during my instrument training I had an instructor that would practice 0 vis takeoffs... basically you get the plane on centerline, put the hood on, then maintain runway heading using the DG. Glad when those were over

Why? Not exactly like it's a "what happens if?" type scenario when it can easily be avoided by a prudent go/no go decision.
DMI
 
AAR90
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RE: Take Off In Fog

Sat Sep 19, 2009 3:10 am



Quoting DashTrash (Reply 10):
Zero viz takeoffs are legal under Part 91. Not the smartest thing to do, but still legal.

Just goes to show you how little Part-91 I actually know. USN/AA training only. I think I've got about 50 hours of actual "civilian" experience.  covereyes  A USN "Special Instrument" rating meant you supposedly had enough experience (1000 hours minimum IIRC) to know NOT to use your "Special" rating.  gasp  Unfortunately, there can be missions that require the risk of plane/crew.  shhh  Thankfully, those are usually few and far between.  sigh 
*NO CARRIER* -- A Naval Aviator's worst nightmare!
 
DashTrash
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RE: Take Off In Fog

Sat Sep 19, 2009 3:45 am



Quoting AAR90 (Reply 15):

No worries. A lot of oddities are legal under Part 91 that aren't under 121 or 135. Under 91, you can start an approach while it's below minimums as well.
 
ThirtyEcho
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RE: Take Off In Fog

Sat Sep 19, 2009 8:35 am

Interesting that some of the first operational "zero-zero" takeoffs were accomplished by B-17 squadrons in England under orders from General Curtis LeMay.

As I understand it, the technique was to set the Directional Gyro to the precise runway heading and then to hold that heading on takeoff without a smidgen of variance. The skill required and the pure guts to attempt it are phenomenal, but it worked.
 
737tdi
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RE: Take Off In Fog

Sun Sep 20, 2009 9:22 am

HGS: Join the modern world. Good grief! Takeoff is one of the most benign parts of the leg. Centerline is held by the ILS and pilot. It's know different then doing an approach in the clouds. Wouldn't advise landing that way but takeoff is awesome if you're Cat III. No danger whatsoever. JMO.
 
dw747400
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RE: Take Off In Fog

Sun Sep 20, 2009 10:16 am

737tdi

you care to let us know what airline has op specs allowing 0/0 takeoffs? I never heard of it.
CFI--Certfied Freakin Idiot
 
ThirtyEcho
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RE: Take Off In Fog

Sun Sep 20, 2009 10:46 am

My great uncle, a WWII B-24 aircraft commander, has added the following to the technique.

The pilot would, upon being certain that the airplane was on the centerline of the runway, set the DG to "0" and hold that until safely off the runway.

Nonetheless, it was pure brass to do that in a British fog.
 
PGNCS
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RE: Take Off In Fog

Sun Sep 20, 2009 1:58 pm



Quoting 737tdi (Reply 18):
HGS: Join the modern world. Good grief! Takeoff is one of the most benign parts of the leg. Centerline is held by the ILS and pilot. It's know different then doing an approach in the clouds. Wouldn't advise landing that way but takeoff is awesome if you're Cat III. No danger whatsoever. JMO.

The lowest I have seen HGS approved for on takeoff is 300 RVR. Do you have a source that an operator is allowed to TO with zero visibility under FAR 121 or its non-US equivalent?

Quoting 737tdi (Reply 18):
737tdi

you care to let us know what airline has op specs allowing 0/0 takeoffs? I never heard of it.

Thank you, I am waiting as well.
 
mmedford
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RE: Take Off In Fog

Sun Sep 20, 2009 3:35 pm



Quoting Brains (Reply 6):
In fact they are RVRs so low that there really is no comperable equivalent in statute miles. My airlines is authorized to depart with RVR 600ft, 600ft, 600ft and RVR 600ft, 600ft assuming runway centerline markings are in good condition and runway centerline lights are operative. High intensity runway lights are also required (without HIRL you cannot get RVR) At least two RVR transmissometers must also be operative.

Thank you for giving the explanation...

I'm TIRED of everyone looking outside and saying it's CAT-IIIc....

It's all about RVR conditions at Touch-down point....

RVR 600 is CAT-IIIb iirc...and on a CAT-III runway you will have high intensity lighting, an ALSF-2 ALS and CCRs keeping everything kosher...
ILS = It'll Land Somewhere
 
CosmicCruiser
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RE: Take Off In Fog

Sun Sep 20, 2009 3:45 pm



Quoting 737tdi (Reply 18):
Centerline is held by the ILS and pilot. It's know different then doing an approach in the clouds.

I've never been taught nor practiced tracking the loc on t/o. In a jet with a Vr of say 155kt you could find yourself all over the runway trying to track it!! Practically you would be better off just flying the rnwy hdg. We all did that in instrument training but more as an excercise of control than something you would really do. My original Instrument Instructor was an old WWII pilot and this may be where this excercise came from. It's not too difficult in a C-150!

Quoting 737tdi (Reply 18):
takeoff is awesome if you're Cat III.

CATIII has nothing to do with T/O. There's t/o mins for every arpt and every airline. As Wilco737 posted there's lighting requirements as well that can effect the mins.
 
pilotpip
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RE: Take Off In Fog

Mon Sep 21, 2009 7:19 pm

You guys all beat me to it with 737tdi. Still waiting to hear what airline he flies for that does takeoffs with the ILS. I'd love to know what happens as you pass the localizer. Bet the passengers love the ride.

We're authorized for 6/6/6. Even then it's incredibly restrictive.
DMI
 
tdscanuck
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RE: Take Off In Fog

Tue Sep 22, 2009 1:17 am



Quoting Pilotpip (Reply 24):
You guys all beat me to it with 737tdi. Still waiting to hear what airline he flies for that does takeoffs with the ILS. I'd love to know what happens as you pass the localizer.

I'm not aware of what airline does it, but I know it's possible. HUD-equipped aircraft that provide runway centerline guidance are using back-course on the localizer to do it.

Tom.
 
mmedford
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RE: Take Off In Fog

Tue Sep 22, 2009 2:15 am



Quoting Tdscanuck (Reply 25):
I'm not aware of what airline does it, but I know it's possible. HUD-equipped aircraft that provide runway centerline guidance are using back-course on the localizer to do it.

Not all locs provide backcourse, especially with shared frequency equipment located on opposite ends of the runway.
ILS = It'll Land Somewhere
 
Alias1024
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RE: Take Off In Fog

Tue Sep 22, 2009 2:22 am



Quoting Tdscanuck (Reply 25):
I'm not aware of what airline does it, but I know it's possible. HUD-equipped aircraft that provide runway centerline guidance are using back-course on the localizer to do it.

Alaska, Horizon, and Southwest are three that I know of. They have 300 RVR minimums out of SEA. I remember one day a couple of years back where the RVR was bouncing between 400 and 500 for a couple of hours. They were the only airlines taking off, while others waited at the gates and on taxiways for improved visibility.

AA might have the same in their HGS equipped 737-800s. Anyone know?
It is a mistake to think you can solve any major problems with just potatoes.
 
pilotpip
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RE: Take Off In Fog

Tue Sep 22, 2009 2:30 am

Are they using LOC or utilizing an RNAV departure?
DMI
 
Alias1024
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RE: Take Off In Fog

Tue Sep 22, 2009 2:51 am



Quoting Pilotpip (Reply 28):
Are they using LOC or utilizing an RNAV departure?

LOC is displayed in the HGS to provide centerline guidance during the takeoff roll. Once you rotate it's just basic IFR flying. Any DP the aircraft is capable of flying can be used.
It is a mistake to think you can solve any major problems with just potatoes.
 
AAR90
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RE: Take Off In Fog

Tue Sep 22, 2009 4:11 am



Quoting Alias1024 (Reply 27):
AA might have the same in their HGS equipped 737-800s. Anyone know?

"Yes" (I know) and "Yes" (300' RVR).

Quoting Pilotpip (Reply 28):
Are they using LOC or utilizing an RNAV departure?

LOC on the ground, weight off wheels = HDG SEL or LNAV initially.
*NO CARRIER* -- A Naval Aviator's worst nightmare!
 
pilotpip
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Joined: Fri Sep 19, 2003 3:26 pm

RE: Take Off In Fog

Tue Sep 22, 2009 4:23 am

Cool, thanks.

I fly one of the most advanced jets out there and they won't let us do any of the fun stuff it's capable of.
DMI
 
sccutler
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RE: Take Off In Fog

Tue Sep 22, 2009 5:07 am

The lowest conditions under which I have ever taken off were 200' and RVR of 1800' or so - as Part 91, again, no legal issue, but a calculated risk on my part, departing from a large field with two long runways, and a climb to bright sunshine in about three minutes.

All worked per plan, no issues, not sure I'd do it again.
...three miles from BRONS, clear for the ILS one five approach...
 
CosmicCruiser
Posts: 2049
Joined: Tue Feb 22, 2005 3:01 am

RE: Take Off In Fog

Mon Sep 28, 2009 9:38 pm



Quoting CosmicCruiser (Reply 23):
I've never been taught nor practiced tracking the loc on t/o.

Well having just completed the 2nd phase of our HUD trg I've learned that yes the loc is used for t/o guidance. However it must be a CATIII rnwy and with CATIII protection. I don't know if it's dampened or not but as posted at rotation it goes away.

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