FS2004 needs CD 4 in the drive. Learn why the correct disc can still fail on modern Windows and which matching no-CD patch to use.
To run the original four-CD edition of Microsoft Flight Simulator 2004 (FS9), put CD 4 in the drive. Installation uses all four discs, but CD 4 is also the play disc checked at launch. If Windows still asks for the correct CD, legacy copy protection is usually the problem.
Why is CD 4 the FS2004 play disc?
The retail FS2004 executable authenticates CD 4 before opening the simulator. CD 1 may display the installer when inserted, but it cannot satisfy the launch check; CDs 2 and 3 will not work either.
Once FS2004 is installed, you do not need to cycle through the set again during normal use. Leave CD 4 in the optical drive or insert it before starting fs9.exe.
What if FS2004 cannot detect CD 4?
If FS2004 requests the correct CD while CD 4 is already inserted, first separate a disc or drive fault from a Windows copy-protection problem.
- Confirm the disc: use the original CD 4 from the FS2004 set, not CD 1 or a copied data disc.
- Check that Windows can read it: open the optical drive in File Explorer. If the files are unavailable, inspect and clean the disc, then try another compatible drive if possible.
- Let the drive initialise: insert CD 4, wait until it has spun up, and then start FS2004. If the computer has several optical drives, try the drive used during installation.
- Account for modern Windows: the retail release depends on old disc-protection technology that modern Windows versions may block. A readable CD can therefore fail authentication even though the drive itself works.
Reinstalling FS2004, using compatibility mode or running it as administrator generally will not restore a copy-protection component that Windows no longer supports.
Can FS2004 run without CD 4?
FS2004 can run without CD 4 when a no-CD executable matching the installed simulator build replaces the disc-checking executable. This should only be used with a legitimately owned copy.
| Installed FS2004 build | Matching option |
|---|---|
| Original, unpatched FS2004 | Use the no-CD replacement intended for the original FS2004 executable. |
| FS2004 with the official 9.1 update | Use the matching no-CD file for FS2004 9.1. |
The official 9.1 update does not remove the CD requirement by itself. Do not put a 9.0 replacement executable into a 9.1 installation, or vice versa; mixing them can prevent FS2004 from starting or leave its files at inconsistent versions. Back up fs9.exe before replacing it and check its version through Windows file properties if you are unsure which build is installed.
What if CD 4 is missing or damaged?
Without a working CD 4, the unmodified retail executable cannot complete its launch check. A no-CD file is a practical option for owners of the original licence, but it does not provide the simulator's missing installation files.
If the complete disc set is gone, obtain legitimate replacement media rather than an isolated disc image. Our explanation of how legitimate FS2004 copies were distributed covers what should be included with a usable copy.