It's Tigoz, but no idea why. I'm not sure what the Singaporean or Taiwanese airlines are using but perhaps it's to be more consistent with those?

Edit. Didn't read the post above

Seems to have changed a few days ago and its 'Tig-Oz ***'

May explain the change

Tigerair Singapore and Scoot to move to single operating licence

Tigerair Singapore’s colours and livery will be consigned to the history books from the middle of 2017 as its operations are integrated with fellow low-cost carrier Scoot under a single brand and operating licence.

The process of bringing together the operations of Tigerair Singapore and Scoot under the Scoot brand was expected to be “realised” in the second half of 2017, the airlines’ said in a statement on Friday. The single brand covered flight scheduling and connections, a common website, contact centre and check-in counters.

The move continues the coming together of the two carriers – both are already under common management after parent Singapore Airlines (SIA) created a single holding company Budget Aviation Holdings to own and manage the two airlines in May 2016

Full story

http://australianaviation.com.au/201...ating-licence/

ADSB prefix changed from TGW to TGG at the same time as the callsign change. TGW/GoCat is still in use by Tiger Singapore

VUD was transferred to Tiger on 31/10

When will VUD enter service after it has completed training

From original article:

“The 4th 737 aircraft will initially be used for crew training purposes in order to support our international services to Bali and then for additional domestic flying over the summer months on popular routes,” the Tigerair spokesperson said.

http://australianaviation.com.au/201...t-in-december/