Landings are Mandatory: Lt. Don Engen and the Mirror Landing System

On January 18, 1911, Eugene Ely landed his Curtiss Pusher biplane on an improvised deck on the stern of the USS Pennsylvania. From that moment, safely landing an aircraft on a ship became the most difficult aspect of naval aviation. The landing site is incredibly small, constantly moving, pitching fore and aft, and rolling side to side. To help guide the aviator to a safe landing, a landing signal officer (LSO) on the stern of the ship would provide direction to the pilot with gestures using colorful hand paddles. In an oddly choreographed dance, the LSO would signal the incoming aircraft to raise or dip a wing, increase or decrease power, and to climb or dive. All of these signals helped guide the aircraft equipped with a tailhook to snag one of a number of wire cables stretched across the flight deck and bring the aircraft to an immediate stop.

For more than 30 years this partnership between LSO and naval aviators remained crucial to aircraft carrier landing operations. Almost overnight this partnership changed. On December 3, 1945, British Royal Navy aviator Lt. Cmdr. Eric “Winkle” Brown made the first operational jet landing on HMS Ocean in a de Havilland Vampire aircraft. Although the landing conditions did not change, jet aircraft changed the calculus of a carrier landing. Early jet engines were very temperamental at slower flight speeds and if they did not receive enough fuel flow, the engine would stop or “flame out.” To avoid this situation, the aviator had to make faster landing approaches, and this dramatically decreased the amount of time for the LSO to signal the numerous corrections needed to safely land on the aircraft carrier.

Numerous engineers began to study how to solve the problem and it had a remarkably simple solution. Cmdr. Nicholas Goodhart, a British Fleet Air Arm aviator and engineer, began working on a solution in 1951. In his office one day, he noticed his secretary’s concaved makeup compact mirror. He drew a horizontal centerline on the mirror with her lipstick and placed it on a fixed angle on his desk. Goodhart focused on the reflection of his nose in the mirror and kept it positioned on the horizontal line. He then walked toward the desk keeping the reflection of the tip of his nose on the centerline. Every time his chin touched down on the identical spot. Thus, the Mirror Landing System (MLS) was born. Goodhart took his idea to the Royal Aeronautical Establishment at Farnborough in late 1953. Here they designed a large five-feet-wide by four-feet-high aluminum concaved mirror with a bright spot center light and a bar of horizontal lights replacing Goodhart’s line of lipstick. This spot would soon be called the ball.

At the very moment that Commander Goodhart and Farnborough were working on the MLS, Lt. Donald Engen of the United States Navy was on assignment at the Empire Test Pilot School. Here, under the guidance of instructors, a small international contingent of pilots honed their flying skills and tested numerous types of aircraft, from the earliest jets to large multi-engine transports. While flying de Havilland Vampires and Gloster Meteors aircraft, Lt. Engen became one of the first naval aviators to evaluate the new MLS system and immediately saw its potential and value. He estimated that it increased the final landing approach in a jet aircraft from five to 20 seconds. He sent a report back to his superiors in Washington recommending the U.S. Navy should adopt the MLS for its aircraft carriers as soon as possible. (Engen went on to have a long and illustrious service in the Navy, ultimately commanding the Atlantic Fleet. He would become the Director of the National Air and Space Museum as a capstone to his lengthy career in aviation in the military, government, and private industry.)

Both countries understood it’s the significance of MLS. The Royal Navy had the first prototype installed on HMS Illustrious in 1953 and the U.S. Navy had them installed on all American aircraft carriers by the end of 1955. The MLS did not eliminate the LSO, which remains a critical part of the landing operations on aircraft carriers. LSOs still evaluate the landing approaches of aircraft to the flight deck and are in constant communication with the aviator making the landing. If the LSO is not satisfied with the approach, they can still order the dreaded wave-off, telling them to abort the landing attempt and try again. The MLS underwent many refinements over the next several decades but now the Joint Precision Approach and Landing System (JPALS) is a navigation and precision approach landing system that guides aircraft onto the aircraft carriers that uses satellite Global Positioning System (GPS) to guide the aircraft to the deck.