An ATC radar facility issues the following advisory to a pilot flying on a heading of 090°: ''TRAFFIC 3 O'CLOCK, 2 MILES, WESTBOUND...'' Where should the pilot look for this traffic?

When ATC says '3 o'clock' while you're on a 090° heading (east), they mean relative to YOUR position. Your 3 o'clock position is to your RIGHT (south). If you're flying east and look to your right (3 o'clock), you're looking south. The traffic being westbound doesn't change where you look - you look south to see aircraft passing south of your position.