Well, we're getting there. What have we got so far?
125/150/150 - count 10 lights and fly (certified for 150 m ops only)
> first REPORTED value is REPLACED by pilot assesment, for 150m and more this is allowed
In this case 1 you took the liberty to assess the initial RVR and replaced the lower reported one with the one suits you.
100/125/125 - no go (if certified for 125 m ops) > under specific additional rules for 125 m ops, RVR must be achieved but pilot replacement of reported RVR is no longer an option
In case 2 you say can't replace 100 with my assessment of 125M.
xxx/125/125 - count 8 lights and fly (if certified for 125 m ops)
> required RVR is obtained in all parts as required by EU OPS
Case 3 NO RVR is replaced with your assessment.
Summary: in all 3 cases pilot conducted the assessment of the initial RVR but for some reasons decided not to replace the reported value with his/her own in case 2. If 125 can be assessed and replace NO RVR reported it's logical that it can be assessed any time regardless of reported RVR. Finally reported RVR 125, below the minimum, was replaced by pilot assessment of RVR 150. Why can't you replace 100 with 125 if you see 8 CL? NO reported RVR or RVR reported below the minima is still a replacement regardless how you twist it. 125 M is a magic number here it seems. Why? It is indeed for EU OPS folks as they believe it provides reasonable assurance that the pilot having 90 VS with RVR 125M will have sufficient time to react and visual cues in both cases RTO and TO to keep the aircraft within the certification confinement 30 ft off the centerline by looking outside. RVR isn't panacea but a reasonable mitigation measure. If we look at the location of the transmissiometers for the TDZ they're right at the RWY beginning and coupla hundreds feet apart so are the others. Does a reported RVR (derived from the automated device) of 125 M guaranties this value achievement along the whole TDZ? Surely NOT hence airbus recommendation NOT to discontinue takeoff in case visual reference is temporarily lost during LVO takeoff. RVR 125 equal 90 M VS is relevant for both takeoff and landing in terms of directional control during low speed regime with high power settings for takeoff and high speed rollout for LVO landing. Therefore I don't see any reason why RVR 125 can't be replaced by PIC as long as he sees 90 m from the flight deck. It appears all this misconception is predicated on the assumption that RVR is derived by automatic device thus being really accurate for the whole rwy portion along with the idea that the remaining 2 RVR values determine how the first one can or must be achieved. Relevant is the key word here. Well, not necessarily the case in the EU OPS land, can be human observation. So in the end what's safer PIC assessment of TDZ RVR of 125 M or human observation of RVR 125? Note this problem doesn't exist in FAA land coz RVR there can only be obtained by a automatic device and 2 RVR are required. Someone smarter than me out there can you please copy paste table air traffic management EU OPS AOM takeoff minima from the Jepp. Thanx.
