Narrative:

Close parallel visual approaches to the left and right runways in use. We were cleared for visual approach and cleared by the tower to land on the right runway. To our left and behind and below us was a CL604 that was cleared for the visual approach to the left runway. The CL604 pilot had a foreign accent. When the tower was about to clear the CL604 to land on the left runway; the tower controller interrupted himself to ask the CL604 a complicated hypothetical question about changing the assigned landing runways for both the CL604 and for us and tried to ask the CL604 pilot if he could do the necessary maneuvering and accept a clearance to land on the right runway. This obviously confused the CL604 pilot who was subsequently unclear as to which runway he was ultimately cleared to land on; even though the tower controller had tried to dismiss his own question and sort of cleared the CL604 to land on the left runway.this was a terrible plan on the part of the tower controller. Both aircraft were below 1;500 feet in a critical phase of flight; the smaller aircraft was behind and below the larger aircraft (us) and was being asked to cross through our wake in order to change runways. We were in the process of final configuration for landing and we could see that the CL604 was still configuring for landing as they still had not extended their landing gear. Adding a cross-over runway change maneuver to two aircraft in such close proximity to each other and doing it in such a circumstance as to force the smaller aircraft to cross behind and below the larger during a critical phase of flight is just stupid. The CL604 pilot was sufficiently confused by the fiasco that they requested clarification of their runway assignment and reiteration of their landing clearance. We observed the CL604's landing gear extending below 500 feet so it seems that their normal procedures were sufficiently disrupted to delay landing gear extension.the tower controller apparently wanted to change our assigned runways for the convenience of ground control operations and shortening the taxi routes after landing. This is an unacceptable reason for putting a smaller aircraft in wake; or even confusing a pilot in a critical phase of flight with unusual and unexpected complicated questions having outcomes that are unacceptable on their face. I don't usually believe that there is ever such a thing as a stupid question; but this tower controller's question was a stupid question. Provide tower personnel additional training about wake turbulence procedures and when it is and is not appropriate to expect pilots to be able to mitigate wake turbulence through visual separation. There was no way that bizjet could have completed the crossover to the other runway and avoided our wake and still completed a stabilized approach and landing. Further; instruct the tower personnel that such a crossover maneuver is the province of aircraft conducting formation flights and that aircraft not identified as a 'flight' are not authorized to conduct formation flight or formation flight maneuvers.

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Original NASA ASRS Text

Title: EMB-170 First Officer reported SFO Tower gave a late runway change to a corporate jet following them on short final that caused confusion.

Narrative: Close parallel visual approaches to the left and right runways in use. We were cleared for visual approach and cleared by the Tower to land on the right runway. To our left and behind and below us was a CL604 that was cleared for the Visual Approach to the left runway. The CL604 pilot had a foreign accent. When the Tower was about to clear the CL604 to land on the left runway; the Tower Controller interrupted himself to ask the CL604 a complicated hypothetical question about changing the assigned landing runways for both the CL604 and for us and tried to ask the CL604 pilot if he could do the necessary maneuvering and accept a clearance to land on the right runway. This obviously confused the CL604 pilot who was subsequently unclear as to which runway he was ultimately cleared to land on; even though the Tower Controller had tried to dismiss his own question and sort of cleared the CL604 to land on the left runway.This was a terrible plan on the part of the Tower Controller. Both aircraft were below 1;500 feet in a critical phase of flight; the smaller aircraft was behind and below the larger aircraft (us) and was being asked to cross through our wake in order to change runways. We were in the process of final configuration for landing and we could see that the CL604 was still configuring for landing as they still had not extended their landing gear. Adding a cross-over runway change maneuver to two aircraft in such close proximity to each other and doing it in such a circumstance as to force the smaller aircraft to cross behind and below the larger during a critical phase of flight is just stupid. The CL604 pilot was sufficiently confused by the fiasco that they requested clarification of their runway assignment and reiteration of their landing clearance. We observed the CL604's landing gear extending below 500 feet so it seems that their normal procedures were sufficiently disrupted to delay landing gear extension.The Tower Controller apparently wanted to change our assigned runways for the convenience of ground control operations and shortening the taxi routes after landing. This is an unacceptable reason for putting a smaller aircraft in wake; or even confusing a pilot in a critical phase of flight with unusual and unexpected complicated questions having outcomes that are unacceptable on their face. I don't usually believe that there is ever such a thing as a stupid question; but this Tower Controller's question was a stupid question. Provide Tower personnel additional training about wake turbulence procedures and when it is and is not appropriate to expect pilots to be able to mitigate wake turbulence through visual separation. There was no way that bizjet could have completed the crossover to the other runway and avoided our wake and still completed a stabilized approach and landing. Further; instruct the Tower personnel that such a crossover maneuver is the province of aircraft conducting formation flights and that aircraft not identified as a 'flight' are not authorized to conduct formation flight or formation flight maneuvers.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.