It does not matter. If they give you 160/4 (or whatever they give), and what should be a 4nm gap to touchdown becomes a 3.7 when you’re on a visual, that’s on you not them. Sure, they’re not regularly sticking a Citation XL 4nm behind an A380 and going “ah, visual, it’ll be grand” but the speeds they’re giving are
not aimed at maintaining wake to touchdown on a visual. That is your job.
Generally speaking in a sequence like that the speed is to make sure you don’t slow early and back the sequence up behind, or to give the tower their requested gaps. It is nothing to do with wake from the aircraft ahead. It is your responsibility to say “UNABLE” if that speed won’t allow you to do what you need to do. You can’t ignore the speed given, but the reason it’s re-stated is the US has a published difference from ICAO where an approach clearance cancels previously iterated speed control (as you correctly stated). Pretty much anywhere else in the world the speed isn’t re-stated because it was never cancelled. The speed is for the sequence, not necessarily for the wake, and definitely not on a visual.
Example 1, normal sequence. You are number 1 for the day (ie, no wake ahead), I have a steady sequence spaced behind you. I clear you for the approach at 12nm and give you no speed. The approach clearance cancels speed, you come back to 140 knots at 10nm (entirely legally) and my sequence behind you is screwed. That’s why speed is re-iterated, nothing to do with wake.
Example 2, LVPs (/LVOs..?). You are number 2, number 1 is on a 3.5nm final. I’m doing 12nm gaps for the tower to get departures away. You’re doing an ILS in this case. I turn you to establish 16nm out and clear you for the ILS. I re-iterate a speed of 160/4 with the clearance because if I hadn’t, you’d have potentially (entirely legally) stayed fast or even sped up and eroded the 12, resulting in tower losing a departure. Speed issued, nothing to do with wake.
Vortex Avoidance Procedures (
FAA AIM) 7-4-6 a):
“Under certain conditions, airport traffic controllers apply procedures for separating IFR aircraft. If a pilot accepts a clearance to visually follow a preceding aircraft, the pilot accepts responsibility for separation and wake turbulence avoidance. The controllers will also provide to VFR aircraft, with whom they are in communication and which in the tower's opinion may be adversely affected by wake turbulence from a larger aircraft, the position, altitude and direction of flight of larger aircraft followed by the phrase “CAUTION - WAKE TURBULENCE.” After issuing the caution for wake turbulence, the airport traffic controllers generally do not provide additional information to the following aircraft unless the airport traffic controllers know the following aircraft is overtaking the preceding aircraft. WHETHER OR NOT A WARNING OR INFORMATION HAS BEEN GIVEN, HOWEVER, THE PILOT IS EXPECTED TO ADJUST AIRCRAFT OPERATIONS AND FLIGHT PATH AS NECESSARY TO PRECLUDE SERIOUS WAKE ENCOUNTERS. When any doubt exists about maintaining safe separation distances between aircraft during approaches, pilots should ask the control tower for updates on separation distance and aircraft groundspeed.” (
The capitalisation is the FAAs, not mine)
Pilot Responsibility 7-4-8:
a) Research and testing have been conducted, in addition to ongoing wake initiatives, in an attempt to mitigate the effects of wake turbulence. Pilots must exercise vigilance in situations where they are responsible for avoiding wake turbulence.
b) Pilots are reminded that in operations conducted behind all aircraft, acceptance of instructions from ATC in the following situations is an acknowledgment that the
pilot will ensure safe takeoff and landing intervals and accepts the responsibility for providing wake turbulence separation.- Traffic information.
- Instructions to follow an aircraft; and
- The acceptance of a visual approach clearance
I’m not posting the entire thing but it goes on to list the techniques it would expect you to use (if in a lighter aircraft fly above the glide path, land longer than the preceding. If in the preceding heavy do not deviate from the nominal glide path etc).
SFO ATC doesn't pass responsibility for wake avoidance spacing to the pilot with the clearance for the approaches or the "maintain visual separation" instructions
That is 100% incorrect. Wake separation on a visual approach is pilot responsibility regardless of any assigned speed.
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edit 12/10/23:
To avoid detailing the main thread again, I’ll add these extra references here for anyone who happens to stumble across this at a later date.
AIM 7-4-5b) note
A common scenario for a wake encounter is in terminal airspace after accepting clearance for a visual approach behind landing traffic. Pilots must be cognizant of their position relative to the traffic and use all means of vertical guidance to ensure they do not fly below the flight path of the wake generating aircraft.
FAA AIM 5-4-23e) Arrival procedures - Separation responsibilities
If the pilot has the airport in sight but cannot see the aircraft to be followed, ATC may clear the aircraft for a visual approach; however, ATC retains both separation and wake vortex separation responsibility. When visually following a preceding aircraft, acceptance of the visual approach clearance constitutes acceptance of pilot responsibility for maintaining a safe approach interval and adequate wake turbulence separation.
AINOnline - The dark side of visual approaches
Pilots are required to see and avoid other traffic during a visual approach. In addition, pilots are responsible for wake turbulence separation.There is no requirement for ATC to provide wake turbulence separation to an aircraft on a visual approach.
NASA Callback 524 September ‘23
Differing from an instrument approach procedure in significant ways, responsibilities such as terrain avoidance, traffic separation, wake turbulence, and cloud clearance migrate somewhat from Controller to pilot during a visual approach.
This one is worth a read as the first example is a Challenger 350 that experienced a wake encounter on final at…SFO.
IFALPA briefing: Visual approach considerations in the USA
For an aircraft operating behind an aircraft that requires wake turbulence separation, the pilot can expect a wake turbulence cautionary advisory from the ATC when the approach clearance is received, however it is impossible for the pilot to accurately assess the position of wake turbulence. There are no tools to predict this phenomena, which is why the wake turbulence separation standards were implemented. By agreeing to reduce those standards (accepting the Visual Approach), the pilot may be increasing the risk of a wake turbulence encounter.
This document is superb, including full coverage of separation/speed/wake responsibilities and requirements with references. It is clear and very well written.