View Full Version : "LOW VIS Proc In Effect"

30th Mar 2011, 08:51
Hi, Question to ATC or Aviation Library Guru(s);

In order for Low Vis Procedures to be In effect, does the RWY/Aerodrome in question have to be Cat II Aerodrome or Better?

ie Some Aerodromes have all the ALS appropriate for Low VIS Take offs and Landing but NO RVR equip.

Does the RWY/Aerodrome have to have RVR transmissiometers for the RWY in Question?

With the said title of thread; what does that statement mean with regards to required aerodrome equipment in order to implement Low Vis Proc?

Please if possible provide CAA or Jepp. Airway Manual References..

Thanks in Advance..


30th Mar 2011, 09:19
Hi, for cat II ops 1 transmitometer is mandatory and for catIII 2 transmitometers or 3 depend of the wx condition according to FAA, but JAA cat III only one transmitometer in needed.


Toby :ok:

30th Mar 2011, 09:22
LVPs are used for two purposes.

First to ensure safety on the ground.....ie. procedures to separate aircraft from other aircraft and vehicles when they cannot see each other; second to protect the integrity of ILS transmissions particularly when Cat ll or Cat lll approaches/landings are being made.

Therefore any airfield can have special procedures in low visibility conditions. The airfield may not need to protect the ILS (ie. it is does not have Cat ll/lll facilities) but it will still need to prevent collisions.

Instrumented RVR measurement is as a general principle only required for ILS Cat ll/lll operations. It is optional for Cat l and in its absence the human observer method remains acceptable.

Low visibility procedures can include a wide variety of matters again dependant on the size/complexity of the airfield and on the ILS Category. They involve the use of additional agl; standby power arrangements; closing/locking access routes which may be acceptable in good visibility but not in low visibility; more use of surface movement radar; limiting vehicle movements on the manoeuvring area; use of more than one person in any vehicle operating on runways; use of particula runway entry/exit points; closing runways/taxiways; enhanced states of readiness of the RFFS; RFFS search procedures; increased intervals between aircraft movements etc etc.

At larger aerodromes, the design and implementation of LVPs is generally the domain of the airport operations department. The actual LVPs being contained within the Aerodrome Manual and Local ATC Instructions.

Generic information on UK LVPs can be found in CAP 168, CAP493, CAP642 Etc.

30th Mar 2011, 12:13
Thanks for the replies;

Referring to the Jepp. Plates alone; how can one determine the Aerodrome in question is capable of LVP departures? if it is only a CAT 1 RWY?

An example of a RWY is ISB, Pakistan. On the 10-9 Aerodrome Taxi chart, JAR-Ops TAKE OFF refers to LVP's must be in force in order to use the stated Minima. However this field does not posses RVR equipment.


30th Mar 2011, 13:22
LVPs should be promulgated by ATC either via the ATIS or normal RTF by Approach (inbound) or tower (outbound).

30th Mar 2011, 13:30
(iii) When the reported meteorological visibility is below that required for take-off and RVR is not reported, a
take-off may only be commenced if the commander can determine that the RVR/visibility along the take-off
runway is equal to or better than the required minimum.

(iv) When no reported meteorological visibility or RVR is available, a take-off may only be commenced if the
commander can determine that the RVR/visibility along the take-off runway is equal to or better than the
required minimum.

You need to check runway lighting
You need to check your OPS Manual
You need to check your aerodrome plates - it should be annotated.

30th Mar 2011, 23:42
Get GBAS...lower Vis.

31st Mar 2011, 00:18

•For Category II and Category III operations, transmissometer systems are strategically located to provide RVR measurements associated with three basic portions of a runway:
•− the touchdown zone (TDZ),
•− the mid-runway portion (MID), and
•− the rollout portion or stop end.
•For Category II operations the TDZ measurement is required, and for Category III operations the TDZ and MID measurements are mandatory. But for CAT III
* *operations with the lowest weather minima, the three measurements are normally required by FAA.
•For CAT III without DH JAR OPS 1 requires only one RVR measuring point on the runway.

* * *CAT II Operations
•− a segment of the approach light system,
•− the runway threshold,
•− the touchdown zone.

* CAT III Operations
•In CAT III operations with DH, the condition required at DH is that there should be visual references, which confirm that the aircraft is over the touchdown zone. Go around is mandatory if the visual references do not confirm this.

* * For this category of operation, the decision to continue does not depend on visual references, even though a minimum RVR is specified. It is nevertheless good airmanship to confirm aircraft position with available visual references. However, the decision depends only on the operational status of the aircraft and ground equipment. If a failure occurs prior to reaching the AH, a go-around will be made. A go around must nevertheless be performed if the autoland warning is triggered below AH.

•Takeoff with RVR less than 400m is considered as LVTO by JAR OPS 1.
•The maximum RVR at Takeoff is quite independent of the aircraft type and aircraft equipment except for very low RVR.
•The Takeoff minima is mainly determined by the airport installation (runway lighting system, RVR measurement system, ...).
•When weather conditions are more severe than the landing minima, a takeoff *alternate is normally required:
* * − within one hour for twins
* * − within two hours for quads
* * − within the maximum approved diversion time for aircraft qualified for ETOPS, but not more than 2 hours (JAR OPS).
* *Above time is determined at the one engine inoperative speed.
•Additional requirements are as follows:
* * − Low Visibility Procedures are in force
* * − High intensity runway centerline lights spaced 15m or less and high intensity edge lights spaced 60m or less are in operation
* * − The 125m RVR value has been achieved for all of the relevant RVR reporting points
* * − Flight crew members have satisfactorily completed training in a simulator approved for this procedure.

I hope this helps.

Toby320 :ok:

31st Mar 2011, 09:20
ABZ and JER both have LVP's and only CAT I runways. I have departed both with very small RVR's so they do have a use!

1st Apr 2011, 11:13
Thanks for the posts everyone..


Your references are the ones I found in JEPP Manual as well as Ops Spec. The Key word(s) there I believe to be "Along" the RWY and Tower must state "LVP's in effect/Force".

Thus if no RVR equip. and PIC is to self assess the RWY, (all other requirements being met) a Taxi down the length of the RWY is required? Would you/others concur?


1st Apr 2011, 11:43
You would need an ATC'er to tell you whether THEY can substitute Met Vis for RVR in setting up LVPs but remember LVPs are about more than just runway lights and vis - all sorts of other factors, like movement restriction, power supplies etc come into play.

Yes, once you have established they are in force a "line-up count the lights" would, I think, do fine.

1st Apr 2011, 13:56
For CAT1 ops (UK) you can have the human observer method, no doubt other authorities will have a similar procedure. This is when a trained observer sits at a specific location in a hut/fire engine at a height of about the average cockpit eg 737. From that point (which is the same each time observations are made), the observer counts the number of runway lights in view. The controller then converts this in a table to a corresponding distance, based on the measured spacing of the runway edge lights. eg 20 lights visible=300 metres. Not all aerodromes will have this conversion table, we no longer have it as we now have full CAT3 facilities and no HOV back up.

LVP's will be put into force based on the prevailing met vis, ours start at 2300meters and ramp up in restrictions of aircraft, vehicles and personel as the met vis drops. This occurs regardless of serviceability of navaids or lighting systems. Eg, 365/24/7 UK ops airfield. No movements scheduled, at night, in fog, aerodrome lights off, LVP procedures will still be in force to protect the airfield.

In the event of total LVP transmissiometer failure we will revert to met vis which must be specifically stated to crew as 'met vis', rather than RVR. Helen49's list above of UK docs is a good starter for ten.

1st Apr 2011, 14:12
For Canada you can read Chapter 4 of the Manual for All Weather Operations found at this link:

Civil Aviation Publications (http://www.tc.gc.ca/publications/app/en/corral.asp?itemid=48311&tpnumber=1490&language=US&source=istore)

Canadian airfield requirements are pretty much standard with the rest of the world as you will see. The manual hasn't been revised since 1990 which is pretty ridiculous, but I guess things haven't changed enough to warrant it.

1st Apr 2011, 17:56
Thanks again for the inputs..

Canada guy, JAR-ops is the ref. in this particular Q+A...

Canada's LVP's well, that is a whole other Kettle of Fish. Not many Canadian airports are ICAO compliant, hence the crazy ass LVP requirements for Dep. and Landing... and Air France's (albeit crazy) lawsuit on the GTA for non-compliance.

Please feel free to comment on Canada's LVP RWY's and ICAO concessions..