AN ALLEGED TRACK VIOLATION MADE BY DEP CTLR WHEN HE CITES A B737 FOR TURNING OUTSIDE OF THE 4 NM RADIUS FROM MDW; IL.

Narrative

DURING PREFLT IMXT 4.0 WAS ENTERED INTO FMC FIX PAGE TO IDENT 4.0 DME AROUND MDW TO COMPLY WITH TURN REQUIREMENTS FOR THE MBW 4 SID. UPON DEP CLB (RWY 22L); STARTED A 30 DEG BANK TURN AT 1300 FT MSL; R TO 110 DEG HDG AS INSTRUCTED BY THE CTLR (TWR). UPON RADAR CONTACT WITH DEP; THE CTLR MADE A NONSTANDARD PHRASEOLOGY STATEMENT THAT NEEDED TO BE VERIFIED; 'COME ON -- GET WITH THE PROGRAM.' AFTER ASKING FOR CLARIFICATION; HE INFORMED US HE SHOWED OUR ACFT POS OUTSIDE THE 4.0 DME ARC. OUR NAV DISPLAYS CLRLY SHOWED US INSIDE THE 4.0 DME ARC. AFTER VERIFYING THIS WITH THE FO'S NAV DISPLAY; I RESPONDED TO THE DEP CTLR THAT WE SHOWED 3.7 DME ON A HDG OF 110 DEGS. HIS RESPONSE WAS HE DIDN'T WANT TO ARGUE ABOUT IT. AFTER PASSING 10000 FT MSL; WE VERIFIED OUR FMC ALIGNMENT; IRU; AND GPS POS -- ALL CHKED GOOD. SUMMARY: DEPARTING RWY 22L WITH AN ASSIGNED HDG OF 110 DEGS (R TURN) ON THE MDW 4 SID STARTING YOUR TURN; AT 1300 FT AT 30 DEG BANK WITH A STRONG SW WIND (240 DEGS AT 45 KTS AT 1000 FT AGL) THIS DAY WILL CHALLENGE THE 4.0 DME REQUIREMENT OFTEN. ACCURACY OF POS IS PARAMOUNT; WHICH SYS ARE TO BE CTLING; ACFT OR ATC? WHICH NAVAID DME IS TO BE USED IMXT/IMDW? THE SID OFFERS BOTH. AN ASSIGNED HDG FURTHER R MAY HAVE BEEN GIVING THIS CTLR THE BUFFER HE WAS LOOKING FOR; AND I APPRECIATE HIS CONCERN FOR US; AND HIS AIRSPACE; BUT I CANNOT OPERATE MY ACFT IN AN UNSAFE MANNER TO COMPENSATE FOR AN INACCURATE POS. THE SID SHOULD CLRLY DEPICT WHICH DME SHOULD BE USED TO IDENT 4.0 DME.