Narrative:

We were cleared into position and hold on runway xl at ZZZ while downfield a B787 was cleared to cross xl and hold short of xr. We were subsequently cleared to takeoff from xl once the B787 cleared our runway. As we accelerated down the runway we passed behind the B787 as they were cleared to cross xr and increased their thrust. Our fairly light aircraft nearing rotation speed was rocked considerably by this thrust. Had we been going faster or weighed less; we might have had more significant control issues. The cause was the above idle thrust or even just the idle thrust of the large aircraft holding between the runways at or near the rotation point of our smaller aircraft's takeoff run. I don't know if they were cleared to cross xr as we passed behind them and they increased thrust or if this was just the idle thrust; but either way it was more than was appropriate for our operation. Either do not hold large aircraft between runways while clearing subsequent (smaller) aircraft for takeoff while passing behind them; or ensure that they do not increase thrust above idle while an aircraft is taking off behind them.

Google
 

Original NASA ASRS Text

Title: ERJ-175 Captain reported the aircraft was rocked on the takeoff roll by jet blast from a taxiing B787.

Narrative: We were cleared into position and hold on Runway XL at ZZZ while downfield a B787 was cleared to cross XL and hold short of XR. We were subsequently cleared to takeoff from XL once the B787 cleared our runway. As we accelerated down the runway we passed behind the B787 as they were cleared to cross XR and increased their thrust. Our fairly light aircraft nearing rotation speed was rocked considerably by this thrust. Had we been going faster or weighed less; we might have had more significant control issues. The cause was the above idle thrust or even just the idle thrust of the large aircraft holding between the runways at or near the rotation point of our smaller aircraft's takeoff run. I don't know if they were cleared to cross XR as we passed behind them and they increased thrust or if this was just the idle thrust; but either way it was more than was appropriate for our operation. Either do not hold large aircraft between runways while clearing subsequent (smaller) aircraft for takeoff while passing behind them; or ensure that they do not increase thrust above idle while an aircraft is taking off behind them.

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.