United Airlines flight 1091 sustained a tailstrike while landing at George Bush Intercontinental Airport (KIAH), Houston, TX. The flight was a regularly scheduled international passenger flight from Mexico City, Mexico to KIAH. According to the flight crew, the captain was the pilot monitoring, and the first officer (FO) was the pilot flying when they were cleared for the visual approach to runway 27 at KIAH. The airplane was in the landing configuration and on a stabilized approach at 1,000 ft. above ground level (AGL). About 60 ft AGL the captain noticed the airspeed begin to decay and stated watch your speed. The FO subsequently pitched the nose of the airplane down and added a little thrust. About 30 ft AGL, due to a higher-than-normal rate of descent the captain commanded flare, flare, flare. The FO flared the airplane which resulted in a firm landing. As the airplane rebounded from the firm landing the spoilers deployed resulting in a nose high attitude. In an effort to correct for the nose high attitude, the captain and FO pushed forward on their respective sidesticks. The FO stated that the ground spoiler deployment coinciding with the firm touchdown resulted in an airplane nose-up pitch attitude. As a result, the pitch attitude increased until the tail struck the runway. After the tailstrike, the remainder of the landing and landing rollout were normal with no risk of runway overrun or excursion. The tailstrike resulted in abrasion damage over an area of about 19 feet long by 1 foot wide along the aft lower fuselage. An inspection revealed substantial damage to the aft pressure bulkhead and frames.