Airship Timer Discrepancies

Time:13.52
Frequency:Since A while (Unsure of actual time but screenshot confirm it has been at least 3 weeks if not since release of airship)
World name:Hyperion
Character name:Yasho Mayo
NPC name:N/A
Monster name:N/A
Class/Level:War 60
Party or solo:Solo
In-game time:11.28pm
Area and coordinates:Private House

I can not break this down into steps so i will have to explain.

I have just noticed for the airships the time to travel + survey doesn't = to the time returned given before sending, for example:
Level 7 Flight
Flight time = 4.5
Return time = 4.5
Survey time = 3.5
Total = 12.5hours flight time
If we round this up to 13 hours to make it easier, the time to return actually shown though is 19 hours 38 minutes and if we round this to 19 hours there is a discrepancy of 6 hours from what it should take by the information given and what it actually take

Connection Specs
- Type of internet connection/provider: DSL Virgin Media
- Modem maker/model number: Superhub 2

PC Specs
-
OS Name Microsoft Windows 7 Ultimate
Version 6.1.7601 Service Pack 1 Build 7601
Other OS Description Not Available
OS Manufacturer Microsoft Corporation
System Name GAMING-PC
System Manufacturer System manufacturer
System Model System Product Name
System Type x64-based PC
Processor Intel(R) Core(TM) i7-3930K CPU @ 3.20GHz, 3601 Mhz, 6 Core(s), 8 Logical Processor(s)
BIOS Version/Date American Megatrends Inc. 0801, 04/07/2014
SMBIOS Version 2.7
Windows Directory C:\Windows
System Directory C:\Windows\system32
Boot Device \Device\HarddiskVolume2
Locale United Kingdom
Hardware Abstraction Layer Version = "6.1.7601.17514"
User Name Gaming-PC\Gaming
Time Zone GMT Daylight Time
Installed Physical Memory (RAM) 32.0 GB
Total Physical Memory 31.9 GB
Available Physical Memory 21.1 GB
Total Virtual Memory 46.3 GB
Available Virtual Memory 31.1 GB
Page File Space 25.9 GB
Page File C:\pagefile.sys


Browser Information
- Name and version of the browser currently in-use: Chrome
- Internet Explorer Version:N/A (Not installed)