Detailed Instructions: This task involves annotating the answer type to a given question that involve some kind of complex reasoning (including numerical reasoning). Note that the questions require looking at more than one part of the passage to answer. There are 3 possible answer types (i) spans, (ii) numbers and (iii) dates. If the answer can be found in the passage, label it as "span". If the answer is a number, label as "number". Similarly, label "date" if you think the answer to the given question is a date.
Problem:Passage: Helicopters are deployed from the air force's 723rd squadron to Danish naval ships. When initiated in 1962, the naval helicopters consisted of a flight of Alouette helicopters of RDAF squadron 722. Primarily for use on the Thetis class in operations in Greenland and Faroe Islands, but also on Absalon class in international operations and Knud Rasmussen class off Greenland as well as participating in exercises. The independent unit was established in 1977 as "Svrnets Flyvetjeneste" operating and Westland Lynx helicopters. On December 6, 2012, the Danish navy officially ordered nine MH-60R Seahawk helicopters, with all to be delivered by 2018, following a competition on the procurement involving the NH90, AgustaWestlands AW159 Wildcat and the AW101 along with Sikorsky's other bid H-92 Superhawk.
Question: When were helicopters first used in the Danish navy?
Solution:
date