A DCA press statement issued last night said the installation and commissioning of the new ILS was part of a project package that included civil and electrical works after an opposition MP said the lack of an ILS had delayed landings to Malaysia's second busiest airport.
But the department also came out to defend the usage of VOR/DME as it said the procedure is similar to ILS.
"This procedure, designed and certified by the Department of Civil Aviation (DCA), permits pilots to approach the runway even in poor weather conditions or at night.
"Similar to the Instrument Landing System approach procedure, the VOR/DME approach procedure requires the pilot to sight the runway by a certain height/distance from the runway to continue the landing," the DCA statement said.
The department also pointed out that if the pilot was unable to sight the runway, the landing would be discontinued.
"It is a standard procedure practised worldwide and therefore certified safe to be used," the statement said.
Some commercial pilots have confirmed that there has been delays because the ILS was not commissioned in the KKIA.
As a regulator, the DCA said it would not certify KKIA for operational use if the facilities did not fulfil the safety requirements set by the International Civil Aviation Organisation and the Malaysian Civil Aviation Regulations.
The DCA also said the lack of ILS should not be compared to the Asiana plane crash at the San Francisco airport last month, noting "suggesting that a similar accident can occur can be very misleading as the causal factors at every accident vary ranging from physical layout of the airport, procedures, the equipment and people".
The San Francisco plane crash on July 6 was a result of the ILS being switched off. The system is a ground based instrument, a combination of radio signals and high intensity lighting that provides precise guidance to the pilot when approaching and landing on any runway.
PKR deputy secretary-general Darell Leiking said earlier the absence of the ILS had caused many flights to be delayed especially during the rainy season.
He said many pilots are finding it difficult to land in bad weather and at night without ILS.
He also claimed that the maintenance of the airport was very poor, including non-lighted runways and overgrown grass surrounding the runway, which covers the signages.
The KKIA handled 5.8 million passengers in 2011. It is the main international gateway into the state of Sabah and, more generally, the island of Borneo.
On Oct 25 last year, the KKIA was closed for a night after the runway lights malfunctioned, forcing several incoming and outgoing flights to be cancelled or rescheduled and leaving many passengers stranded. - August 3, 2013