After a rest period, during which he was a test pilot for Hawker Siddeley and then the Gloster Aircraft Company, he returned to operational flying in April 1944 with No.

The squadron was equipped with the Hawker Tempest and when the Germans began launching V-1 flying bombs at England, it was tasked with intercepting them.

After completing his schooling, he worked in Wellington for the New Zealand Government and later moved to Dunedin, where he was a clerk for the Tourist Bureau.

[4][5] Umbers formally joined the Royal New Zealand Air Force on 24 November 1940, enlisting as an airman pilot with the service number 404003.

When operating interception missions at night, it would use its radar equipment to locate enemy aircraft, then illuminate them with the searchlight once spotted so that an accompanying Hurricane could endeavour to shoot it down.

[9][10] On 22 December, while Umbers, now holding the rank of flying officer, and his wingman were on patrol, a Dornier Do 217 medium bomber was spotted 5 miles (8.0 km) away.

[2] The squadron was switched to offensive operations in April 1943 and started flying to occupied Europe, escorting bombers.

[1][9] Umbers was subsequently awarded the Distinguished Flying Cross (DFC),[5] which was officially announced on 7 September in The London Gazette.

In air combat, Flight Lieutenant Umbers has displayed great keenness and determination, setting a fine example.

He has shared in the destruction of an enemy bomber.On 24 September Umbers damaged a Fw 190 southeast of Trouville and shortly afterwards was taken off operations.

He was briefly assigned to the headquarters of Fighter Command in a staff role but in late October he was sent to Hawker Siddeley, the aircraft manufacturer, as a test pilot.

Umbers fulfilled a similar role for the Gloster Aircraft Company from November through to April 1944, at which time he was posted to No.

3 Squadron's operational role was to fly intruder missions to France in preparation for the forthcoming invasion of Normandy.

[15] However, when the Germans started launching V-1 flying bombs at England, beginning on the night of 12–13 June,[16] the squadron was tasked to deal with the threat as the Tempest was the fastest fighter plane available to the RAF.

[18] The published citation read: This officer has led his flight on very many sorties during which military transport, railway communications, ammunition dumps and other targets on the ground have been attacked with excellent results; on one occasion 8 locomotives were destroyed.

By his great skill and unbeatable determination, Flight Lieutenant Umbers has played a worthy part in the successes achieved.

[22] On 1 January 1945, the Luftwaffe launched Operation Bodenplatte, a coordinated strike against the Allied airfields in the Low Countries.

Umbers, in the air at the time and leading a reconnaissance flight, intercepted and destroyed a Fw 190 and a Messerschmitt Bf 109 fighter near Helmond.