fore decided, including Awards 615, 757 and later ones, recognize that there is a line of demarcation between those that are within the scope and those that are without; that each case presents a factual situation which upon examination causes it to be cast to the one side or the other. That line has never been completely described, and perhaps because of the varying nature of undertakings, it never can be ascertained in a set and certain way. The general principles can be determined, but the particular facts of each controversy must be weighed and tested in the light of the scope of the contract and from that basis a decision can be reached as to whether it is within the scope of the Contract or forms an exception thereto.

A managerial judgment must be permitted whenever the case involves a highly skilled force, and other incidents that the Carrier probably could not provide from its force and equipment. Award No. 2338."

"* * * It is not vigorously contended and its submission inferentially concedes that even though the Scope Rule makes no mention of the work attached to hours of service and working conditions referred to therein, necessary, reasonable and practical recognition of what is preserved to the employes through its provisions requires the implication that such work as at the time of the negotiation and execution of the Contract its employes were customarily engaged upon was contemplated by its terms. We go further and hold that we regard it as covering all work in the Maintenance of Way Department except such, there being no exceptions contained in the scope rule or elsewhere in the Agreement, as in view of the exigencies confronting the Carrier can under our decisions be properly excepted under what, in judicial parlance is known for want of a better term, as 'operation of law'. Perhaps better for our purposes would be to describe it as that which from the very nature of the work involved the Carrier does not possess sufficient equipment and skill to perform under the exigencies of the situation prevailing and with which it is required to deal. * *

Fairness requires, and we readily concede it, that in the building of bridges and construction of other projects involving services of a specific character under conditions where the Carrier does not possess the skilled force and other things such as equipment it could not provide or would not be justified in maintaining for rare occasions on which they would be required, the Carrier should be, and is, permitted to go outside and contract for their construction. * *

lead sleeves. The Carrier's regular signal maintainer, has assistant, the Claimant, (an extra signalman) and his assistant, together with a telephone and telegraph maintainer (not under the Agreement) were used to assemble and make available the necessary materials. All of these employes remained on the job until 10:30 p.m., when the repairs were completed, except the Claimant and his assistant, who were relieved at 3:30 P. M. to return to their headquarters.

It is the contention of the employes that the retention of the Western Union workmen was a violation of the effective Agreement and that by reason thereof the Claimant was improperly relieved from duty before the completion of the repairs.

The Scope Rule of the Agreement provides that "Signal Work" is understood to refer to work generally recognized as such. The Carrier's contention is, however, that there were no employes under the Signalmen's Agreement possessing the requisite skill to perform such intricate service as was here involved; and that over a long period of time such highly skilled operations have been contracted out with the acquiescence of the Organization.

Mere acquiescence of the employes in the continuance of a practice calculated to ignore the proper application of the scope rule of an agreement will not ordinarily constitute an estoppel, though It may result in a bar to the collection of retroactive penalties. We think it is also proper to say that when a carrier contracts out work which would appear to be within the scope of an agreement, it must assume the burden of establishing that such conduct was reasonably justified by the facts. Instead of assuming that burden this Carrier has sought to shift its obligation to the Organization. We quote from the Carrier's statement of its position:

"Prior and subsequent to the performance of the duties described herein the employes failed to conclusively demonstrate in any manner that Claimant employe or any other employe coming within the scope of the Signalmen's Agreement at this location was capable of performing the specialized task of applying a lead sheath to a cable."

We must hold, therefore, that the Carrier has failed to establish that the work here in question was excepted from the Agreement, or that its signalmen were not competent to perform such service.

FINDINGS: The Third Division of the Adjustment Board, after giving the parties to this dispute due notice of hearing thereon, and upon the whole record and all the evidence, finds and holds:

That the Carrier and the Employe involved in this dispute are respectively carrier and employe within the meaning of the Railway Labor Act, as approved June 21, 1934;

That this Division of the Adjustment Board has jurisdiction over the dispute involved herein; and

That the Carrier violated the Agreement.

AWARD