The Air Force launched a Midgetman missile to a Pacific Ocean target in the first successful test flight of the mobile weapons system.

"Initial indications are all systems worked properly, and we are extremely pleased with the performance of the missile," Col. Howard J. Mitchell, the program director, said in a statement after the Thursday test.Major contractors on the Midgetman include Morton Thiokol Inc. of Brigham City, Utah, which is building the first-stage rocket motor;

Aerojet Nevada Rocket Operations of Sacramento, Calif., which is developing the second-stage motor; and Aerospace Production Group of Magna, Utah, which is building the third-stage motor.

The 53-foot-long missile was ejected from an above-ground canister at 11:33 a.m. PDT and the first-stage rocket motor ignited, sending it on a 4,600-mile flight to Kwajalein Missile Test Range, the Air Force said.

The flight of the unarmed missile lasted 30 minutes.

The first test of a Midgetman failed on May 11, 1989, when it began tumbling shortly after launch and had to be destroyed by controllers.

The Midgetman, formally known as the Small Intercontinental Ballistic Missile, is 46 inches in diameter, weighs 37,000 pounds and is designed to carry a single warhead.

The complete system includes the missile and a mobile launcher consisting of a tractor and launch trailer designed to travel on and off roads.

Thursday's flight was intended to test missile performance, flight subsystems, ground software, flight software, the canister launch system and launch sequence procedures, the Air Force said.

The canister system employs the "cold launch" technique in which the missile is hurled out of a tube by gas pressure before the motor fires.

The Midgetman has been in development since 1983. The first Midgetman flight two years ago was cut short when the missile began tumbling 70 seconds after launch and then was blown up by a destruct command.

Martin Marietta Corp. is overseeing assembly and testing and providing support services. The truck launcher is being developed separately by the Boeing Aerospace Co. in Seattle.